DK SMITHSONIAN SUPERSIMPLE CHEMISTRY

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CHEMISTRY

THE ULTIMATE BITESIZE STUDY GUIDE

Contents Basic Chemistry

The Scientific Method 26 Atoms
27 History of the Atom
10 How Science Works 28 Electron Shells
11 Scientific Issues 29 Electronic Structure
12 Scientific Risk 30 Elements
13 Validity 31 Isotopes
14 Experiment Variables 32 Mixtures
15 Safe Experiments 33 Compounds
16 Equipment 34 Formulas
17 Planning Experiments 35 Deducing Formulas
18 Organizing Data 36 Equations
19 Math and Science 37 Balancing Equations
20 Units of Measurement 38 Purity
21 Charts and Graphs 39 Formulations
22 Conclusions 40 Dissolving
23 Errors and Uncertainty 41 Grinding
24 Evaluations 42 Solubility
43 Calculating solubility
44 Chromatography
46 Filtration
47 Evaporation
48 Crystallization
49 Simple Distillation
50 Fractional Distillation In the Laboratory

Elements States of Matter

52 The Periodic Table 91 Solids
54 History of the Periodic Table 92 Liquids
55 Hydrogen 93 Gases
56 Metals 94 Diffusion in Liquids
58 Group 1 Physical Properties 95 Diffusion in Gases
59 Group 1 Chemical Properties 96 Changes of State
60 Group 2 97 Heating and Cooling Curves
61 Group 3 98 State Symbols and Predicting States
62 Transition Metals
64 Lanthanides Nanoscience and
65 Actinides Smart Materials
66 Carbon
67 Group 4 100 Nanoparticles
68 Group 5 101 Properties of Nanoparticles
69 Group 6 102 Uses and Risks of Nanoparticles
70 Group 7 103 Thermochromic and
71 Group 0
Photochromic Pigments
Structure and Bonding 104 Shape Memory Materials
105 Hydrogels
73 Ions
74 Ionic Bonding
75 Ions and the Periodic Table
76 Dot and Cross Diagrams
78 Ionic Structures
79 Ionic Properties
80 Covalent Bonding
81 Representing Covalent Bonds
82 Simple Molecules
83 Properties of Simple Molecules
84 Polymers
85 Covalent Network Solids
86 Allotropes of Carbon
87 Fullerenes
88 Metallic Bonding
89 Pure Metals and Alloys

Quantitative Chemistry The Chemistry of Acids

107 Relative Formula Mass 130 The pH Scale
108 Using the Percentage Mass Formula 132 Acids
109 Moles 133 Bases
110 Mole Calculations 134 Indicators
111 Conservation of Mass 135 Neutralization
112 Changing Mass 136 Titrations
113 Moles and Equations 137 Strong and Weak Acids
114 Balancing Equations Using Masses 138 Dilute and Concentrated Acids
115 Limiting Reactants 139 Reactions with Bases
116 Calculating Masses in Reactions 140 Reactions with Metal Carbonates
117 The Volume of Gas 141 Making Insoluble Salts
118 Empirical Formulas 142 Making Soluble Salts
119 A Reacting Masses Experiment
120 Calculating the Reacting Mass Metals and Their Reactivity
121 Water of Crystallization
122 Calculating Water of Crystallization 144 The Reactivity Series
123 Concentration 145 Reactions with Acids
124 Titration Calculations 146 Reactions with Water
125 Atom Economy 147 Reactions with Steam
126 The Advantages of Atom Economy 148 Extracting Metals with Carbon
127 Percentage Yield 149 Redox Reactions
128 100% Yield 150 Group 7 Displacement Reactions
151 Ionic Equations
152 Metal Displacement Reactions
153 Electrolysis
154 Extracting Metals with Electrolysis
155 Half Equations
156 Extracting Aluminum in Industry
157 Electrolysis of Water
158 Electrolysis Experiments
159 Electrolysis of Aqueous Solutions
160 Electroplating

Energy Changes Organic Chemistry

162 Chemical Reactions 198 Organic Compounds
163 Combustion 199 Naming Organic Compounds
164 Oxidation 200 Hydrocarbons
165 Thermal Decomposition 201 Alkane Properties
166 Exothermic Reactions 202 Hydrocarbon Combustion
167 Endothermic Reactions 203 Crude Oil
168 Energy Transfer: Solutions 204 Fractional Distillation
169 Energy Transfer: Combustion 206 Cracking
170 Exothermic Reaction Profiles 207 Cracking Paraffin
171 Endothermic Reaction Profiles 208 Alkenes
172 Calculating Energy Changes 209 Addition Reactions
173 Simple Voltaic Cells 210 Isomers
174 Voltaic Cells 211 Combustion of Alkenes
175 Batteries 212 Testing for Alkenes
176 Fuel Cells 213 Addition Polymers
177 Inside a Fuel Cell 214 Representing Addition Polymers
215 Alcohols
The Rate and Extent of 216 Properties of Alcohols
Chemical Change 217 Uses of Ethanol
218 The Production of Ethanol
179 Rates of Reaction 219 Carboxylic Acids
180 Collision Theory 220 Carboxylic Acid Reactions
181 Reaction Rates and Temperature 221 Esters
182 Reaction Rates and Concentration 222 Condensation Polymers
183 Reaction Rates and Surface Area 223 Polyesters and Polyamides
184 Reaction Rates and Catalysts 224 DNA
185 Rate of Reaction Graphs 225 Proteins
186 Reaction Rates and the Volume of Gas 226 Carbohydrates
187 Reaction Rates and Changes in Mass 227 Hydrolysis of Polymers
188 Reaction Rates and Precipitation
189 Reaction Rates and Acid Concentration
190 Calculating Reaction Rates
191 Reversible Reactions
192 Equilibrium
193 Energy Transfer in Reversible Reactions
194 Equilibrium and Temperature
195 Equilibrium and Pressure
196 Equilibrium and Concentration

Chemical Analysis Using Resources

229 Testing for Oxygen 258 Ceramics
230 Testing for Carbon Dioxide 259 Composites
231 Testing for Hydrogen 260 Synthetic Polymers
232 Testing for Cations Flame Tests 261 Making Polymers
233 Testing for Cations Precipitation Reactions 262 Alloys
234 Testing for Anions Carbonates and Sulfates 263 Sustainability
235 Testing for Anions Halides and Nitrates 264 Corrosion
236 Testing for Chlorine 265 Preventing Corrosion
237 Testing for Water 266 Finite Resources
238 Flame Emission Spectroscopy 267 Renewable Resources
239 Interpreting Spectroscopy Charts 268 Recycling
269 Life Cycle Assessment
Chemistry of the Earth 270 Potable Water
271 Seawater
241 Earth’s Structure 272 Wastewater
242 Tectonic Plates 273 Treating Wastewater
243 Rocks 274 The Haber Process
244 The Rock Cycle 275 Reaction Conditions
245 The Atmosphere 276 Fertilizers
246 Measuring Oxygen 277 Producing Fertilizers
247 The Carbon Cycle
248 The Greenhouse Effect 278 Glossary
249 Human Activity 282 Index
250 Global Warming 288 Acknowledgments
251 Carbon Footprints
252 Carbon Capture
253 Nuclear Energy
254 Air Pollution
255 Pollution Problems
256 Acid Rain

The Scientific
Method

10 The Scientific Method

How Science Works Key Facts

Scientists want to explain how and why things ✓ Scientists have a testable idea
happen using facts—such as what happens when
two elements react together, or when atoms bond. called a hypothesis.
They do this by thinking logically in a step-by-step
process called the scientific method. This method ✓ Scientists predict what may
is used in all fields of science, including chemistry,
biology, and physics. happen during an experiment.

1. Observation ✓ If a hypothesis is supported by an

Scientists study experiment’s conclusion, it is
something that they accepted as fact.
don’t understand.
✓ Scientists present their discoveries,

however the media may present
their own theories on the same
subject in a different way.

9. Publication 2. Making a hypothesis

A scientist’s results may Scientists ask a question
be published in about what they are
observing.
scientific journals
publicly. The media ? 3. Making
may also share the
8. Refining predictions
results with bias Scientists predict
(leaning toward a experiments an answer to the
certain perspective). If the data doesn’t
answer the question, question.
7. Peer review scientists may change
and repeat the
Other scientists experiment to find out
decide whether why that may be.
they feel the data
answers the question.

6. Drawing 4. Planning

conclusions experiments
Scientists decide Scientists plan
whether they feel experiments (see page 17)
to test their hypothesis.
their data
answers their
question (see

page 22).

5. Collecting data

Scientists gather
their data as

evidence for their
hypothesis.

The Scientific Method 11

Scientific Issues Key Facts

Science can improve our lives, from finding new ways ✓ New scientific discoveries may raise
to generate energy to creating new medicine to help
the sick. This new knowledge can lead to positive unexpected concerns.
developments; however, they may also raise issues that
may not have been obvious at first. It’s important to be ✓ These concerns need to be understood
aware of these issues so we can understand the full
impact of new scientific discoveries on the world. by people who are affected by the

scientific discovery.

✓ Science may raise moral issues to which

it can’t provide answers for.

Building dams People living in towns that have
Dams are designed to provide us with been cut off by the dam may feel
easy access to water, as well as many personally disadvantaged.
other benefits. However, their creation
has led to unexpected issues.

Dams cause nearby areas to flood,
including local forests, which can
disturb natural habitats—this is an
environmental issue.

Diverted roads can create social issues Building the dam may
by cutting off access to some towns, cost a lot of money, which
or splitting up communities. can be an economic
issue for governments.
Ethical Issues in Science
Fishing in rivers with dams can be
Science aims to provide answers to questions, affected negatively, because the dam
but there are some questions that can’t be
answered by science. Some scientific disrupts fish migration patterns.
developments present ethical issues—
whether something is right or wrong. For New gene Cell functions
example, the field of genetics can provide added normally
cures for diseases, but some people believe
that modifying life in this way is wrong. Cell with New gene suppresses
faulty gene faulty gene

12 The Scientific Method Key Facts

Scientific Risk ✓ Hazards may cause harm to others or

There is a chance that scientific discoveries may be the environment
dangerous or cause harm—this is called risk. This is
measured by how likely the negative effects are to ✓ The chance that hazards cause harm
happen and how serious they can be if they do. Risk
can be obvious, such as coming into contact with a is called risk.
toxic substance. Risk may also be hard to foresee,
such as a product containing a new substance that ✓ People assess for themselves
has properties we are not sure about.
how risky a certain scientific
Oxygen Hydrogen development might be in their life.

Carbon Substances in sunscreen
Formulations (see page 39) such
as some sunscreens can contain a
harmful substance called octinoxate.
This is an artificial compound that
blocks harmful radiation from the Sun.

Octinoxate is a long chain
of molecules.

Unforeseen hazard of octinoxate Thyroid gland
The use of sunscreens that contain
octinoxate is very risky for health and Strands of sunscreen
for the environment. Recent studies Bleached coral
have shown that it disrupts hormone
production in the thyroid gland, and it
can wash off a swimmer’s skin into the
ocean, bleaching coral, and harming
the environment.

Healthy coral

Validity The Scientific Method 13

Scientists won’t trust a experiment’s Key Facts
findings if the experiment produces
different results when repeated, ✓ An experiment is repeatable if the same person recreated
or if the experiment can’t be
conducted by other scientists. the experiment using the same equipment and they
If an experiment is repeatable and collected similar results.
reproducible, and the results answer
the hypothesis, then the experiment ✓ An experiment is reproducible if different people
is considered valid.
conducted the same experiment with different equipment
Repeatable and similar results were collected.
If the same person repeated
the experiment using the same ✓ If an experiment is repeatable and reproducible, and the
equipment and collected
similar results, the experiment results answer the hypothesis, then the experiment is
is repeatable. considered valid.

Reproducible First try Second try
If a different person conducted
the experiment using different 30 ml 30 ml
equipment and observed
similar results, the experiment 12/13/14 12/13/14
is reproducible.

Same results?
If the experiment is repeated
and reproduced and produces
the same results, then the
experiment is valid.

Precise Equipment Precise Imprecise
measurements measurements
It’s important to use equipment that can
measure quantities precisely. For example, Precise Imprecise
a pipette where you can clearly see
measurements in increments of 1 ml along
the side (rather than a measuring cylinder
with increments of 5 ml) will ensure that
you can measure the same quantity when
you repeat your experiment, so your
results are likely to be the same.

14 The Scientific Method Key Facts

Experiment ✓ Variables are things that can affect
Variables
the results of your experiment.
When testing a hypothesis, scientists conduct
experiments by changing one thing and seeing how it ✓ The independent variable is the thing
will influence something else. Sometimes, they need
to keep some things the same so they can understand that you change during an experiment.
how one thing affects the other. These things are
called variables, and by identifying ✓ The dependent variable is the thing
them, scientists ensure their
experiments are fair. that you measure when you change
the independent variable during
Examples of variables an experiment.
This simple experiment involves
hydrochloric acid reacting ✓ The controlled variables are the things
with iron sulfide to create
hydrogen sulfide, and has an that you try and keep the same during
independent, dependent, and an experiment.
controlled variable.
Control Experiments
The amount of hydrochloric acid is
the independent variable. There are things that may be impossible
to control, such as the temperature of the
room or the time of day. A control
experiment is the same experiment, but
where nothing is changed. The results of
this are compared with your original
experiments so you can see the effects
of things outside your control.

The amount of
hydrogen sulfide
produced is the
dependent variable.

The amount of iron
sulfide is the

controlled variable.

Safe Experiments The Scientific Method 15

It’s important to conduct experiments safely Key Facts
to avoid any accidents happening. Sometimes,
chemistry experiments can involve corrosive ✓ Experiments can be unsafe.
acids or heating substances, so there’s a risk of ✓ Equipment or procedures should be
being injured or burned. The safety equipment
shown here helps make experiments safer. planned for to keep experiments as
safe as possible.
Protecting your eyes
Glasses protect your eyes Protecting your body
from small particles during Lab coats protect your body from
explosive chemical reactions. harmful substances.

Protecting your hands
Gloves protect your skin
from accidental spills of
corrosive substances.

Safe heating Dangerous Chemicals
Water baths are a safer, and
more efficient, way of heating Some chemical substances can be
substances by submerging dangerous. Look out for labels on bottles that
them in hot water instead of provide different types of warnings.
using an open flame from a
Bunsen burner. Flammable Corrosive Toxic

Preventing fires
Heatproof mats prevent
fires from starting in
the laboratory.

Heatproof mat

16 The Scientific Method

Equipment Key Facts

When conducting an experiment, choosing the ✓ It’s important to understand each piece of
right equipment is important to collect the
results you need appropriately and safely. the equipment’s function.

Chemistry equipment ✓ It’s important to be able to draw each piece
Beakers, test tubes, gauze, tripods,
heatproof mats, and Bunsen burners are of equipment as a simple line drawing.
some of the most common equipment
used in chemistry experiments. Gauze spreads heat
from the Bunsen burner.
A glass beaker can A test tube can
help you heat help you store A Bunsen burner
substances safely. substances. produces a flame
that you can use to
heat substances.

A tripod keeps
substances
elevated away
from a Bunsen
burner’s flame.

A heatproof mat
helps stop fires.

Drawing Equipment

Sometimes, you may also need to draw your experiment in an exam.
Simple line drawings of each piece of equipment are shown below.

Gauze

Beaker Test tube Tripod Bunsen burner
Heatproof mat

Planning The Scientific Method 17

Experiments Key Facts

Every stage of an experiment must be carefully ✓ Experiments require planning and are
planned out. You may need to carry out
experiments in the classroom or explain how you usually conducted in at least six stages.
would conduct an experiment for an exam. Every
experiment is different, but there are six common ✓ The independent, dependent, and
stages. Most of these stages involve choosing your
variables (see page 14), which is very important. controlled variables are chosen carefully.

Neutralization reaction
This experiment involves adding
hydrochloric acid to sodium hydroxide
and measuring the temperature.

1. Decide on your dependent 3. Gather, or describe, the

variable. For this experiment, the equipment you need. For this
experiment, you would need the
dependent variable is the
equipment
temperature. shown on
page
168.

2. Decide on your

independent variable. For this

experiment, the independent

variable is the amount of

hydrochloric acid you add.

5. Plan to repeat the

experiment to ensure the

results are repeatable.

6. Decide 4. Decide

on whether you on your control

are performing a control variables. For this experiment, the

experiment (see page 14). control variable is the amount of

sodium hydroxide you start with.

18 The Scientific Method Key Facts

Organizing Data ✓ Data is the information collected

Data is the information that you collect from from experiments.
your experiment. Data is usually numbers or
measurements, such as the volume of liquid collected. ✓ Data must be organized so that it can
Data is collected using your equipment. Organizing
data into tables helps you to make sense of it. be easily reviewed.

✓ Calculating the mean of a data set

can help you to get an average.

Anomalous results are pieces of Inaccurate data are ranges
data that are very different from the of data that are very
rest and are not close to the mean.
different from the rest.

Data set 1 Data set 2 Data set 3 Data set 4
22 20 27 35
21 21 21 34
22 22 22 35

22 21 22 35

Calculate the mean from each data set to
find the average. Anomalous results are not

included when calculating the mean.

Significant Figures This number gives five This number gives two
significant figures. significant figures.
Some numbers in your data may
include many decimal points, such as 24.823 25
24.823. In an exam, you may be asked 1 2 345
to round your answers to a certain 12
number of significant figures, such as
two significant figures. In this example,
you would give your answer as 25.

The Scientific Method 19

Math and Science Key Facts

Chemistry sometimes involves a bit of simple ✓ You must know how to rearrange
mathematics. It’s worth brushing up on your
multiplication and division skills, as well as a mathematical equation.
what’s listed here.
✓ You must know how to calculate
How to rearrange an equation
The subject of a formula is what is being figured out. a percentage.
You can change the subject by performing the opposite
calculation on what you want the new subject to be. ✓ You must know how to calculate

a ratio.

area = base × height area
base = height

The area is the Make the base the subject of The base is new the
subject of the the formula by dividing instead subject of the formula.
formula. of multiplying by height.

How to calculate a percentage
A percentage is a way of expressing how much
a value is of the total, which is represented as
100%. Calculate this by dividing the value by
the total, and then multiply this by 100.

Relative atomic mass of sodium is 23, 46 Percentage of sodium
and there are two atoms of sodium in × 100 = 43% by mass in sodium
sodium carbonate. 23 multiplied by 2 carbonate.
106
is 46. This is the value.
90.
The relative formula mass of the
compound that contains sodium
carbonate is 106. This is the total.

How to calculate ratios M+ ÷
The ratio is a number representing the proportion of
something in relation to something else. For example,
here is the ratio of hydrogen atoms in an ammonia
molecule to the number in hydrogen molecules.

NH3 : H2 3:2 +/− MR M− 9 × −
% 6 =
7 8 5
. 3
√ C 4 2 +
1
There are three There are two hydrogen AC 0
hydrogen atoms in a atoms in a molecule of
molecule of ammonia. hydrogen gas.

20 The Scientific Method Key Facts

Units of ✓ Units help scientists measure things
Measurement
using certain equipment.
Standard units are a universal set of measurements
that help scientists measure things in the same way, ✓ Using the same units helps scientists
allowing everybody to understand and compare
collected data. One unit describes one measurement compare data with each other.
of a particular quantity. Here are some metric units.
✓ Different pieces of equipment

measure things using different units.

Weight Length
Scales are used to Rulers are used to measure
measure something’s how long something is in
weight in grams or centimeters or meters.
kilograms.

Quantity Base unit Quantity Base unit
weight length
gram (g) kilogram (kg) centimeter (cm) meter (m)

Volume Time 0000:0:000
Beakers are used Stopwatches and timers
to measure the can be used to measure
volume of liquids in time in seconds,
cubic centimeters minutes, or hours.
or cubic meters.

Quantity Base unit Quantity Base unit
volume cubic centimeter (cm3) cubic meter (m3) time
seconds (s) minutes (m)

Converting Units

Mole Units can be converted between different levels using
Unique beakers are a number called a conversion factor.
used to measure the
mole, which is both ×1,000
the mass and volume
of substances g kg
(see page 109). mm m
m3 dm3
Quantity Base unit mol/dm3 mol/cm3
mole mole (mol)
÷1,000

Charts The Scientific Method 21
and Graphs
Key Facts
On its own, data may not tell you enough
about what you’ve found. Charts and graphs ✓ Charts and graphs are a clear, visual way of
are a visual way of representing your data,
and certain graphs are more useful than representing your data.
others, depending on your data.
✓ Bar charts are useful for presenting data that is

in categories.

✓ Line graphs are useful for presenting data with

variables that changed.

Bar charts Relative atomic mass (u) 20 A single bar is
A bar chart is used for 16 used for one
discontinuous data 12 element.
(such as data collected 8
in categories), such as 4
shoe size, eye color, or 0
relative atomic masses
of elements. Carbon

Boron Oxygen

Elements

Line graphs Volume of liquid (cm3) 30
Line graphs are useful for
continuous data (or data 20 Data is plotted on the
collected over time), 10 graph, and a line is
such as the volume of drawn to connect
liquid produced over the data together.
time. This line graph is
showing a positive 0 4 68 10
correlation (rising trend 2
from left to right). Time

Linear scales are chosen
to fill the graph paper.

22 The Scientific Method Key Facts

Conclusions ✓ It’s important to make concise

Reviewing your data can help you make a clear conclusions about your data.
statement about what happened in your experiment—
this is a conclusion. Identifying patterns, such as, over ✓ Only comment on what the data
time, higher temperatures evaporate more liquid, can
help form these conclusions. However, you can’t is showing, not why you think
assume why this is. It’s important to check whether that may be.
your conclusion supports your hypothesis.
✓ A pattern in your data doesn’t mean
Hypothesis
For the below flame test, the hypothesis is that a something is causing something else.
metal will turn a Bunsen burner’s flame yellow.

Hypothesis supported Hypothesis unsupported

You can conclude that the You can conclude that the
flame turned yellow, so flame did not turn yellow,
so this conclusion does not
this conclusion supports support your hypothesis.
your hypothesis.

What Conclusions Variable 2 ? Variable 2
Can’t Tell You
Variable 1
Even though you can conclude Variable 1 Variable 1 Variable 2
that the flame turned yellow in Your data may show that
the presence of a metal, you The relationship between The relationship between one variable directly
can’t assume why that is in two variables may be up two variables may be influences another.
your conclusion. This may to chance—one does not influenced by an unknown
inspire you to do more affect the other. third variable.
experiments to find out more.

Errors and The Scientific Method 23

Uncertainty Key Facts

There is always uncertainty around your data. ✓ Uncertainty is a measure of how many errors
Uncertainty represents whether your data
were collected accurately and precisely. are in your results.
Two factors influence uncertainty: the limits
of your equipment (quantitative error), ✓ Quantitative errors (numeric errors) and
and poor planning (qualitative error).
qualitative errors (non-numeric errors)
contribute to uncertainty.

✓ Uncertainty in your results can be corrected

using the formula shown below.

Choosing equipment This pipette This pipette This pipette
Quantitative errors can measures liquid measures liquid measures liquid
be avoided by choosing in increments of in increments of
equipment that can in increments 2 ml, so is close 1 ml, so is precise
measure things as of 10 ml, so is to being precise enough for this
precisely as possible. imprecise for enough for this
A piece of equipment’s experiment.
ability to measure the needs of experiment.
precisely is called its this experiment.
resolution. For example,
if you need to measure 10 ml
liquids in quantities of
1 ml, choose a pipette that
can measure amounts in
single milliliters.

2 ml 1 ml

Avoiding random errors 1ml Uncertainty formula range
You may accidentally measure First try 2
a liquid inaccurately, especially 1ml uncertainty =
if the measurements are very
small. This might mean Accounting for uncertainty
your results are slightly If you measure 1 ml of liquid with a measuring
different each time you cylinder, the range of possible values may be
take a measurement, and anything between 1.5 and 0.5 ml. The
is unavoidable. uncertainty formula takes this into account.

± 0.5 = 1.5 − 1
2

Second try

24 The Scientific Method Key Facts

Evaluations ✓ Evaluations can be done to highlight

Reflecting back over an experiment helps you what could be improved about
understand what may have gone wrong and how the experiment.
things could be improved. There are six stages to
carrying out an evaluation, and they can be used ✓ Further experiments may be
to plan further experiments.
conducted after evaluations have
1. Evaluate whether the been made.

experiment was valid and 2. Evaluate whether the
fair (see page 13).
results allowed you to make a
6. Make further predictions conclusion (see
page 22).
for further experiments.

?

Making evaluations
There are six main stages of
thought you should undergo
when making evaluations of
your experiment.

5. Suggest 3. Take a

improvements to look and see if

the experiment. you have any anomalous

results, and think about

why that happened.

4. Review your

conclusion with the

information gathered from

the previous three steps to

see if you want to change it.

Basic
Chemistry

26 Basic Chemistry Key Facts

Atoms ✓ All matter is composed of atoms.
✓ Atoms are very small and have a
Everything in the Universe is made of atoms. They are
the smallest unit of elements (see page 30), such as gold, radius of 0.1 nanometers.
carbon, or oxygen, and all matter is made of elements. All
atoms are microscopically small. They vary in size, but a ✓ Atoms are made up of even smaller
typical atom is one-ten-millionth of a millimeter. A piece
of paper is about one million atoms thick. subatomic particles called protons,
neutrons, and electrons.
Atomic structure
All atoms are made of subatomic Electron shells
particles called protons, neutrons,
and electrons. Each atom has
a nucleus in the middle with
electrons orbiting around it.

The nucleus is made up Neutron Radius
of protons and neutrons, Proton of 0.1 nm
and is 1/100,000 of the

size of the atom.

Electrons orbit
the nucleus.

What’s Inside an Atom? Proton Charge Mass The charges and the
Neutron +1 1 masses given here are
Protons and neutrons have the Electron 0 1 all relative to one
same mass, and together they −1 0 another, and are not
make up the atom’s total mass. exact measurements.
Electrons are much lighter,
smaller, and have almost no
mass. Protons have a positive
electric charge, neutrons have
no charge, and electrons have
a negative electric charge.

Basic Chemistry 27

History of the Atom Key Facts

In the 5th century BCE, ancient Greek philosopher ✓ The concept of atoms dates from
Democritus thought that matter was made from tiny
particles called atoms. In 1803, British chemist John around 500 BCE in ancient Greece.
Dalton suggested that each element is made of
different atoms, based on the way different gases ✓ Ideas about what atoms are made
react with one another.
of have changed over time.
Changing atom models
Scientists created many different models of how ✓ Scientists including John Dalton,
atoms were structured. Over time, these models
were revised and updated by other scientists. J.J. Thomson, Ernest Rutherford,
Neils Bohr, James Chadwick, and
many others contributed to how
atoms are understood.

1. Spherical model 2. Plum pudding model
The first model of the atom was theorized J.J. Thomson discovered electrons in
by John Dalton in 1803. Dalton suggested 1904. He suggested the Plum pudding
atoms were solid particles that could not model, in which negatively charged
be divided into smaller parts. electrons are embedded in a positively
charged ball.

The gold foil experiment Gold atom Beam of positively
In 1909, New Zealand scientist Ernest charged particles
Rutherford performed the gold foil experiment. passed straight through
He fired tiny positively charged alpha particles some areas of atoms.
at a sheet of gold foil. The results revealed the
existence of a positively charged nucleus in the Positively charged
center of all atoms. nucleus repels positively
charged particles
Gold foil because they have
the same charge.

Alpha source beaming Tiny negatively Beam of positively
positively charged particles. charged electron charged particles
deflected by positively
3. Nuclear model charged central nucleus.
Ernest Rutherford proposed an atomic
model of a positive nucleus in the 4. Modern nuclear model
center of a scattered cloud of electrons. Neils Bohr found that electrons orbit
He later discovered the proton as the the nucleus. Later, James Chadwick
positive charge in the nucleus. discovered neutral (no charge)
neutrons in the nucleus. This led to
Edge of atom the latest atomic model used today.

28 Basic Chemistry Key Facts

Electron Shells ✓ Electrons orbit the nucleus in shells.
✓ Each shell can hold a fixed
Electrons are small particles of an atom. They orbit
around the atom’s nucleus in pathways called shells. maximum number of electrons.
A small atom, with only a few electrons, only has one
or two shells. Larger atoms, such as radium, have lots ✓ Electrons must fill their innermost
of electrons, and need more shells to hold them all.
Chemists draw shells as rings around the nucleus. shells first before filling their
outer shells.
Electron shell rules
In atoms with 20 electrons or fewer, The second shell
such as aluminum atoms, each shell can hold up to eight
can hold a fixed number of electrons. electrons.

Electron

The first shell
can hold up to
two electrons.

Proton

Neutron

The third shell
can hold up to
eight electrons.

Electronic Structure Basic Chemistry 29

You can use information found on the periodic Key Facts
table (see pages 52–53) to calculate the
electronic structure of an atom. Scientists can ✓ An atom’s electronic structure lists
display an atom’s electronic structure by using
drawings (see page 28) or list the numbers of the number of electrons in each
electrons held in each shell—for example: 2, 8, 3. of its shells.

Method one: using the atomic number ✓ An electronic structure can be
Take the atomic number (total number of electrons)
and share out the electrons between the shells until calculated if you know the number
they are filled (following the rules on page 28) to work of electrons and shells within
out the electronic structure. each atom.

✓ The electronic structure can be

calculated for 20 elements using
two methods.

13 1. Look up aluminum’s 2. Follow the electron shell 3. Aluminum’s electronic

Al atomic number on the rules on page 28. You have structure is 2, 8, 3.
periodic table. Aluminum’s 13 electrons to share out
Aluminum atomic number is 13. between three shells.

Method two: using periods and rows
An element’s period number is equal to the number of
shells its atoms have. An element’s group number is
equal to how many electrons are in the outermost shell.

1. Aluminum is 2. Aluminum is in 3. Aluminum’s inner 4. If aluminum’s inner shell has two

in period 3, so group 3, so its atoms two shells must be full electrons and its outer shell has three
its atoms have have three electrons in because inner shells electrons, there are eight electrons left
their outermost shells. must be filled first. for its middle shell. So, aluminum’s
three shells. electronic structure is 2, 8, 3.

1 0

1 2

1H He

Hydrogen 7 Helium

2 3 4 5 6

3 4 5 6 7 8 9 10

2 Li Be B C N O F Ne

Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon

11 12 13 14 15 16 17 18

3 Na Mg Al Si P S Cl Ar

Sodium Magnesium Aluminum Silicon Phosphorus Sulfur Chlorine Argon

19 20

4K Ca

Potassium Calcium

30 Basic Chemistry Key Facts

Elements ✓ Elements contain one type of atom.
✓ The number of protons in an atom’s
Elements are pure substances that cannot
be broken down into simpler substances. nucleus determines the element.
Each one has unique physical and chemical
properties. The number of protons in an atom ✓ 118 different elements have been
determines the element, and this number is
known as the element’s atomic number. discovered so far.

Inside elements
Pure samples of each
element have one type
of atom.

Pure europium Pure osmium
contains only contains only
europium atoms. osmium atoms.

Osmium

Pure gold contains
only gold atoms.

Europium Gold

The Periodic Table Each square
represents
Scientists arrange all the an element.
elements in order of atomic
number into a chart called the
periodic table. Elements are
grouped together depending
on their properties, often as
varying choices of colors. Read
more about the periodic table
on pages 52–53.

Isotopes Basic Chemistry 31

Isotopes are different forms of the same element, Key Facts
where the atoms have the same number of protons
but a different number of neutrons. For example, a ✓ Isotopes are forms of an element.
typical magnesium atom has 12 protons, 12 ✓ The number of neutrons in an atom’s
neutrons, and 12 electrons. But some magnesium
atoms have more neutrons. They are still magnesium nucleus determines the isotope.
atoms, just a different isotope of magnesium.
✓ Elements can have multiple isotopes.
Isotopes of magnesium ✓ Isotope names are written as the
Magnesium has three isotopes; magnesium-24,
magnesium-25, and magnesium-26. Their abundance is how element name followed by the total
common they are on Earth, and is given as a percentage. number of protons and neutrons.

Magnesium-24 atoms Magnesium-25 atoms Magnesium-26 atoms Magnesium
have 12 neutrons in have 13 neutrons in have 14 neutrons in
their nuclei, and an their nuclei, and an their nuclei, and an
abundance of 78.99%. abundance of 10%. abundance of 11.01%.

Measuring Isotopes Relative atomic mass formula: Isotope 2
Isotope 1
You can use this formula to
calculate the average mass Ar = (mass number × abundance) + (mass number × abundance)
of all isotopes of an element,
which is known as the relative This is the sum of all 100
atomic mass (Ar). If you know abundances and is always 100.
the isotope mass numbers
(their total amount of protons
and neutrons) and abundances,
you can calculate the Ar
for any element.

32 Basic Chemistry Key Facts

Mixtures ✓ A mixture is made up of two or more different

Sometimes, elements can be mixed or elements or compounds.
combined together, but they do not react
or bond to form new compounds. This type ✓ Mixtures contain elements and/or compounds
of combination of two or more elements or
compounds is called a mixture. For that are not chemically bonded together.
example, air is a mixture of oxygen,
nitrogen, and other gases. ✓ The elements or compounds keep the properties

Iron and sulfur mixture they had before they were mixed.
This mixture is made of sulfur powder
and iron filings. The two elements do not ✓ Elements in a mixture can be separated from one
react or bond when they are mixed, and
can be easily separated using a magnet. another without using chemical reactions.

Iron Sulfur Iron and sulfur
mixture

Atoms in Mixtures

As the different elements in S S S
a mixture are not chemically SS S S
bonded, their atoms do not Fe S
mix in a regular pattern or Fe Fe Fe Fe Fe Fe
shape. Instead, they form a Fe Fe Fe Fe Fe Fe
random pattern. Fe Fe
Fe Fe Fe Fe
Fe Fe Fe Fe
S
Iron (Fe) atom SS Sulfur (S) atom

S SS

SSS

Compounds Basic Chemistry 33

Different elements can react with one Key Facts
another to chemically bond together,
making new structures called ✓ Most elements can undergo a reaction to
compounds. Most substances around
us are made up of different compounds. form compounds.

Iron and sulfur compound ✓ Compounds are made of atoms of one or
The elements iron and sulfur react and
bond together to form the compound more elements that are bonded together.
pyrite. Iron is magnetic, sulfur is brittle,
but pyrite is neither magnetic nor brittle. ✓ The properties of a compound are different

from the properties of the separate elements
it’s made of.

✓ Elements in a compound can only be

separated using chemical reactions.

Iron and sulfur
undergo a reaction.

Iron Sulfur Iron and sulfur
compound
Atoms in Compounds
Fe S Fe S Fe S Fe S Iron (Fe)
When atoms bond together to S Fe S Fe S Fe S Fe atom
make a compound, they create Fe S Fe S Fe S Fe S
a new structure. This gives the S Fe S Fe S Fe S Fe
compound new physical and Fe S Fe S Fe S Fe S
chemical properties. For S Fe S Fe S Fe S Fe
example, in pyrite, iron and
sulfur atoms bond together in
a regular three-dimensional
arrangement.

Sulfur (S)
atom

34 Basic Chemistry Key Facts

Formulas ✓ Formulas show which elements

Formulas are a simple and quick way of writing out a compound is made up of.
what elements are in a compound. They use words
or symbols (see page 53), and sometimes numbers. ✓ There are many types of formulas,
There are many different types of formulas. Below
are four formulas for sodium chloride. but you need to know four: word,
chemical, atomic, and structural.
Word formula
The names of the elements in the Chemical formula
compound are listed in full, instead The symbols for each element
of using their symbols.
are used. There is no space
Sodium chloride between each symbol.

NaCl

Na is the Cl is the
symbol for symbol for
chlorine.
sodium.

Atomic formula Structural formula
The symbols for each element The symbols for each element are
and the outline of each atom connected by a dash that represents
show what is in the compound.
a bond between each atom.
Na Cl
Na – Cl
Cl atom
The dash represents a
bond between an Na
atom and a Cl atom.

Common Formulas

Familiarize yourself with Carbon dioxide CO2 Carbon monoxide CO There are two
these common chemical Ammonia NH3 Hydrochloric acid HCl chlorine atoms in
compounds. A formula may Water H20 Calcium chloride CaCl2 a molecule of
have small numbers next to Methane CH4 H2SO4 calcium chloride.
the symbols. This tells you Sulfuric acid
how many atoms of this
element are in a molecule
of this compound.

Deducing Basic Chemistry 35
Formulas
Key Facts
Atoms bond with each other so they can fill their
outer shells with electrons. Each element has a ✓ Valence is a number that relates to how
valence, which shows how many electrons an
atom of that element will gain, lose, or share an atom will bond with other atoms.
when it bonds with another atom or atoms.
✓ A valence chart lists valences for elements

in groups.

✓ The “drop and swap” method allows you to

figure out formulas for compounds made
of elements using valences.

Figuring out valences
Elements in the same group on the periodic table have
the same valence, listed in a valence chart. Formulas
for compounds such as water can be determined
using a valence chart and the drop and swap method.

Hydrogen
atom

Group 12345670

Water molecule Oxygen
atom
Valence 1 2 3 4 −3 −2 −1 0
O2−
For example: H+ Drop
H2
H+ Write hydrogen’s valence O2− Write oxygen’s valence
smaller and slightly smaller and slightly
above its symbol. above its symbol.

OSwap

1. Hydrogen (H) is in Group 1, so 2. Oxygen (O) is in Group 6, so its 3. Drop the valences from above
its valence is one. Hydrogen atoms valence is minus two. Oxygen atoms the symbol to below. Swap the
may lose one electron, giving it a gain two electrons to fill their outer valences to the other element.
positive charge. The “one” isn’t shell, giving them a negative charge of This provides the formula for when
written. Instead, write a plus sign 2. In this instance, the number and the hydrogen and oxygen combine:
to indicate the positive charge. charge sign is added to the symbol. H2O, or water.

Transition Metals Iron(II) chloride
solution is a
The transition metals (see pages 62–63) clear liquid.
fill in the middle part of the periodic table,
between Group 2 and Group 3. You can’t Iron(III) chloride
tell what their valence is by looking at the solution is an
table. Transition metals often have more
than one valence. For example, iron (Fe) amber-colored liquid.
can have a valence of either 2 or 3. These
valences are written using Roman Iron II Iron III
numerals, such as Iron II and Iron III.

36 Basic Chemistry Key Facts

Equations ✓ Equations show how

Equations use symbols (see page chemical reactions change
53) and formulas (see page 34) to reactants into products.
show the changes that happen to
substances during a chemical ✓ Equations can be made
reaction. The substances that react
together are called reactants. The up of words, symbols,
chemical reaction is represented by or formulas.
an arrow. The new substances that
form after the reaction has taken ✓ Equations may contain
place are called products.
symbols to indicate the
state of matter.

Sodium chloride This reaction is often contained
These equations show within a flask because it
the elements sodium produces a lot of heat and light.
and chlorine (reactants)
reacting to form sodium
chloride (product).

Word Sodium + chlorine Sodium chloride
equation

Formula 2Na + Cl2 2NaCl2
equation
Reactants Product
The reaction is
represented by an arrow.

State symbols Sodium and chlorine atoms bond to
Equations may also contain state symbols (see make a solid substance; sodium chloride.
page 98). These are in parentheses that show
the states of matter of the substances. Chlorine atom

Sodium
atom

Sodium (s) + Chlorine (g) Sodium chloride (s)

This state symbol (g) shows This state symbol (s) shows that
that chlorine is a gas. sodium chloride is a solid.

Basic Chemistry 37

Balancing Equations Key Facts

During chemical reactions, atoms (see page 26) of ✓ Equations must be balanced, with the
different elements (see page 30) rearrange to form
new products. To reflect this, the two sides of a same number of atoms on both sides,
chemical equation must be balanced so they both because atoms are never lost or
have an equal number of atoms. If an equation is gained during reactions.
unbalanced, numbers can be added to balance it.
Charges must also balance (see page 151). ✓ Unbalanced equations can be

An unbalanced equation balanced by adding numbers in front
This equation shows the elements hydrogen and of the formulas, until both sides have
oxygen reacting to make water. It is an unbalanced the same number of atoms.
equation, because it has two oxygen atoms on the
left but only one on the right.

This “H” is This small “2” This “O” is the This is the
the formula represents two formula for oxygen. formula for water.
for hydrogen. hydrogen atoms.

H2 + O2 H2O

Two hydrogen There are two oxygen
atoms atoms on the left-hand
side, but only one on
the right-hand side.

How to balance an equation 2. Add a big “2” to the right-hand
Keep adding numbers to the
equation until it is balanced. side. This adds another water
molecule. Recount. This now
1. Add a big “2” to the left-hand matches the number of atoms
on the left-hand side.
side next to hydrogen. This doubles
2H2O
the number of hydrogen atoms.

2H2 + O2

38 Basic Chemistry Key Facts

Purity ✓ A pure substance contains only one type

Pure substances contain only one type of of element or compound.
element (see page 30) or compound (see page
33). For example, pure water contains only water ✓ Purity can be tested by checking when a
molecules, a compound of hydrogen and oxygen.
However, substances are rarely completely pure. substance will melt or boil.
They usually have other elements or compounds
mixed into them that we can’t see. ✓ Impurities in a substance usually lower the

Checking for purity melting point and increase the boiling point.
Pure substances have fixed melting and boiling
points. For example, water melts at 32°F (0°C) ✓ The closer a substance’s boiling and
and boils at 212°F (100°C). Impure water will
melt or boil over a range of temperatures. melting points are to the pure substance’s
boiling and melting points, the purer it is.

Key Temperature (°F) Impure water
212
solid
liquid 32 Pure water
gas
Time
Pure water melts from a
solid into a liquid at 32°F.

Pure water boils
from a liquid into

a gas at 212°F.

Useful Impurities

Impurities aren’t always
bad—they can be useful. For
example, dissolving salt in water
increases the water’s boiling
point, making food cook faster.
Adding salt to icy roads makes
the ice melt much quicker so
that roads are safer to drive on
during the cold months.

Salt and water Salt and ice

Formulations Basic Chemistry 39

A formulation is a type of mixture (see page 32) that Key Facts
is made for a specific use. Each ingredient added to
the formulation gives it a specific property. ✓ Formulations are mixtures that contain
Formulations can be everyday substances, such as
nail polish, medicine, laundry detergent, and paint. exact amounts of specific ingredients.

Paint ✓ Formulations are made for a purpose
Paint is an example of a formulation.
Three of its ingredients have useful and work in a particular way.
functions. The four chemicals in paint are
added in carefully measured amounts so ✓ Chemists working in different industries
that it works at its best. Any more
or less of one chemical and often create and test formulations.
the paint may be too
runny or too thick.

Binder Pigment

The pigment is the
chemical that gives

paint its color.

Solvent dissolves the Additives
ingredients and makes

the paint runny.

Binder holds the
paint together in
place on the surface
it’s painted on.

Solvent A small amount
of additives may

include things
like chemicals to

prevent mold.

40 Basic Chemistry

Dissolving

Dissolving happens when one substance
breaks apart into tiny particles and
becomes completely mixed throughout
another. Substances that dissolve, such as
sugar, salt, or tablets, are called solutes.
Substances that can dissolve solutes,
such as water or ethanol, are called
solvents. Together, they form a solution.

Dissolving sugar Sugar is
Sugar dissolves easily in water. a solute
Once dissolved, the sugar can
no longer be seen.

Key Facts Water is a
solvent
✓ Solutes are substances that are

being dissolved.

✓ Solvents are liquids that dissolve

solutes.

✓ Solutions are created when solutes

dissolve in solvents.

✓ Not all substances can dissolve.

Molecules Separate 1. At first, the solute, such as 2. Gradually, water 3. When the solute is

Many substances dissolve salt, holds together because molecules surround the salt completely dissolved,
in water. Water molecules
are attracted to many of the bonds between its particles, breaking them it is evenly spread out
different kinds of
molecules and atoms, atoms or molecules. away from each other. through the solvent.
breaking them apart easily.
You can make solutes
dissolve faster by heating
and stirring mixtures.

Grinding Basic Chemistry 41

Grinding breaks down large chunks of a solid, Key Facts
such as rocks or crystals, into a fine powder.
This helps the powder dissolve in a liquid much ✓ Grinding breaks substances into
quicker. Grinding can also speed up a reaction
by increasing a reactant’s surface area. smaller particles.

Separating compounds ✓ Grinding helps substances
A mortar and pestle can be
used to grind rock salt into dissolve in liquids quicker.
smaller pieces.
✓ Grinding helps speed up reactions.

Mortar

Smaller
pieces of
rock salt
crystals

Pestle

Rock salt crystal
chunks.

Increasing Surface Area Pestle is twisted
with force

Chemical reactions happen much 24 cm2 48 cm2
quicker if the surface area of a solid
reactant increases. For example, Rock salt Fine salt
grinding a 8 cm3 cube of rock salt with
a surface area of 24 cm2 breaks into 1. The surface area of a
lots of 1 cm3 cubes with a total surface
area of 48 cm2. This provides double rock salt cube may
the surface area for the reactant to measure about 24 cm2.
react with, speeding up the reaction.

2. Take a mortar and 3. Now, the combined

pestle and grind it surface area of the rock

into smaller chunks. salt is about 48 cm2.

42 Basic Chemistry Key Facts

Solubility ✓ Solubility is a measure of how much solute

The solubility of a substance is a measure of how will dissolve in a solvent.
much of it can be dissolved in a solvent (see page
40). Usually, the higher the temperature it is heated ✓ The solubility of most solids increases as
to, the higher its solubility. Solubility is measured in
grams per solute per 100 grams of solvent (g/100 g). you raise the temperature.

Solute ✓ You can measure solubility by evaporating

the solvent away from a solution and
measuring the mass of the
remaining solute.

Solvent Solution

85.5 85.5 Mass stays the same
A solution’s mass is the same
as the combined mass of the
solute and solvent before it
has been dissolved.

Different temperatures, different rates
The higher the temperature, the more solvent can be dissolved
in a solute. You can conduct a simple experiment by varying the
temperature and measuring the mass of salt dissolved in water.
You should keep the mass of water and number of stirs the same.

10g of salt dissolved in water 50g of salt dissolved in water 100g of salt dissolved in water

Beaker

Bunsen
burner

Water temperature at 50°F (10°C) Water temperature at 68°F (20°C) Water temperature at 86°F (30°C)

Calculating Basic Chemistry 43
Solubility
Key Facts
The solubility of a substance can be measured precisely,
and you can calculate it if you know the mass of the ✓ Solubility is measured in grams
solvent (such as water), and the mass of the maximum
amount of solute (such as salt) that will dissolve in it. of solute per 100 grams of
solvent, written as g/100g.
How to calculate solubility
Weigh the solution. Then, ✓ To calculate solubility, you need
evaporate the solvent from
the solution and weigh the the mass of the solvent and the
solute left behind. Subtract mass of the solute dissolved in it
that from the mass of the when no more will dissolve.
solution to get the mass of
the solvent.

Solution Solute after solvent
has evaporated

solubility = mass of solid (g) × 100
(g per 100 g of solvent)
mass of water removed (g)

Solubility curves You can estimate the solubility of The substance’s
The solubility of a substance any amount of a substance by solubility limit
at different temperatures drawing a line from the y axis.
can be marked on a graph,
known as a solubility curve.
Different substances will
have unique solubility curves.

100

Solubility / g per You can estimate
100 g of solvent the solubility at any
temperature by drawing
a line from the x axis.

The vertical, or y axis, 0 100 The horizontal, or x axis,
shows the solubility in Temperature / °F shows the temperature in
g/100 g, from 0 to 100. °F, from 0 to 100.

44 Basic Chemistry

Chromatography Key Facts

Chromatography is a process that separates ✓ Chromatography is a way of separating
compounds (see page 33, such as dyes) from a mixture
(see page 32, such as ink). There are two parts, or compounds from mixtures.
phases. The stationary phase is the paper, as this does
not move. The mobile phase is the liquid or gas that ✓ Chromatography involves a stationary
flows through the stationary phase, separating the
mixture. The compounds are separated because they phase and a mobile phase.
have different solubilities (see page 42).
✓ Some chemicals move further through
Making a chromatogram
All you need to make a chromatogram is filter paper, a pencil, the stationary phase than others.
a selection of inks, some water, and a container to keep the
water in. Follow these steps to create a chromatogram. A ✓ The Rf value shows how far the
chromatogram is the physical result of chromatography.
chemicals move compared to the
1. Use a pencil to draw a line mobile phase.
near the bottom of the paper. Add
spots of ink to the line. Hang the 2. The mobile phase (water) rises up
paper above a dish of water, with the stationary phase (paper), carrying
the paper’s edge in the water. the ink with it. The more soluble a
solute is, the higher it will rise.

Clip suspended
on rod holds the

paper in place.

Ensure you use pencil,
not pen, to draw the
baseline—if you use
pen, its ink will interfere
with the experiment.

Place water below the
baseline so the inks are
not washed away.

The paper is the
stationary phase.

The water is the
mobile phase.

Basic Chemistry 45

Calculating Rf Value Rf = Distance traveled by one dye (cm)
Solvent front (cm)
The Rf value is a measurement
of how far a substance travels Example for purple dye: 0.9 = 4.5 cm
through the stationary phase 5 cm
(paper), compared to how far the
mobile phase (water) travels. If the
chromatogram is repeated using
ink with the same dye, and the Rf
value is the same, the substances
are pure.

3. The inks collect in spots at different 4. Use a ruler to measure the
distances up the paper. The resulting distance each dye has traveled from
the baseline. The furthest distance
pattern is called a chromatogram. the mobile phase has traveled is
called the solvent front. Use a pencil
to mark the solvent front on the paper.

Solvent front 4 cm
Blue 4.5 cm
4.8 cm
Purple 5 cm
Red

Baseline

46 Basic Chemistry Key Facts

Filtration ✓ Filtration separates insoluble

Filtration is used to separate a liquid from an insoluble solvents from liquids.
solid. An insoluble solid is one that doesn’t dissolve (see
page 40) in a particular liquid (solvent), such as water. ✓ Filtration is one of several methods
The mixture is poured though filter paper, which has
tiny holes in it. Water molecules are small enough to of separating mixtures.
pass through the tiny holes, but the larger insoluble
solid particles are caught by the paper. ✓ If a solid can’t dissolve in a particular

Filtering sand solvent, it is said to be insoluble in
Sand is an insoluble solid in that solvent.
water. Filtration can be used
to separate sand from water. Sand (insoluble solid)
sticks to the filter paper.

Conical-shaped
glass funnel holds
filter paper.

Water and sand Clear water
is a mixture. (solvent) filtered
into the beaker.

Separating Mixtures Magnet Iron filings (solid)
are attracted to
There are other ways of separating Sand (solid) is not the magnet.
mixtures, depending on the attracted to the magnet.
properties of the substances they
contain. For example, a magnet
can be used to separate a mixture
of magnetic iron filings and
nonmagnetic sand.

Evaporation Basic Chemistry 47

Evaporation happens when liquid molecules Key Facts
break their bonds to become a gas. Water
slowly evaporates at room temperature—that’s ✓ Evaporation is the steady change
why wet clothes dry when hung up. Heating
water makes the water evaporate faster. of a liquid (below its boiling point)
into a gas.
Boiling water
If you heat a liquid to its boiling ✓ Boiling happens when a liquid
point, it boils—all the liquid
evaporates quickly into a gas. is heated and it quickly changes
into a gas.

✓ Heat gives the molecules in the

liquid more energy, which breaks
the bonds between molecules.

Steam
(water vapor)

Bubbles of
gas rise to
the surface.

Separating Mixtures Water molecules are Heat makes the Copper sulfate
held together by bonds between (solid solute)
bonds as a liquid. liquid water break.

Evaporation can be 1. A solution of 2. The solution 3. The water turns into
used to separate a
solvent from a solute copper sulfate in starts to boil, forming a gas, leaving copper
dissolved in it (see
page 40). They can water is heated. water vapor. sulfate behind.
be separated because
the solvent has a
higher boiling point
than the solute.

48 Basic Chemistry Key Facts

Crystallization ✓ Crystallization separates a solute

Crystals are solid structures with atoms (see page 26) from a solution.
that form a regular three-dimensional lattice pattern.
Solutions (see page 40) that are gently heated and ✓ Crystallization involves slowly
left to cool may form crystals—this process is called
crystallization. The longer it takes to cool, the larger heating to dissolve the solute, and
the crystals that form, in most cases. then cooling, a solution to cause the
solute to crystallize.
Copper sulfate crystals
When a solution containing ✓ The crystal’s size, and sometimes the
copper sulfate is slowly heated
and then left to cool, navy-blue shape, depend on how quickly the
crystals form. solid cooled.

Copper sulfate Copper sulfate crystal
solution (soluble solid)

How Crystals Form Before being heated, molecules When water is heated and has
in a mixture of copper sulfate evaporated, the copper sulfate
When solutions with dissolved and water are randomly and molecules are concentrated enough
solids are heated, the liquid evenly distributed. to connect and build crystals.
evaporates and the solute’s
molecular structure becomes
more rigid. If the solution is
heated quickly, large crystals
form. If the solution is heated
slowly, small crystals form.

Basic Chemistry 49

Simple Distillation Key Facts

Distillation is a process that uses heat, evaporation, ✓ Simple distillation separates one
and condensation to distill (collect) a liquid from a
solution. The solution is heated, and the liquid with liquid from a solution.
the lower boiling point will evaporate, leaving
behind the solute with the higher boiling point. ✓ Simple distillation only works if the
The evaporated gas is cooled and condensed
back into a liquid, and then collected. liquid has a lower boiling point than
the solid dissolved within it.

✓ Simple distillation leaves you with

a pure substance.

Separating water from ink Cool water vapor
condenses in the tube.
Mixtures such as water and ink can

be separated by distillation. The

mixture is heated to pure water’s
boiling point (212°F/100°C).

2. Hot water 3. Cool water is

vapor rises pumped around a
through the Liebig condenser
tube and cools.
tube to help the
hot water vapor
cool and condense.

4. Pure, clear water

runs down the tube and
collects in the beaker.

Water in

1. The mixture of Water out

water and ink in a
flask is heated by a
Bunsen burner.

Water has a lower
boiling point than
the ink, so it boils
and evaporates
into vapor.

50 Basic Chemistry

Fractional Distillation Key Facts

In the Laboratory ✓ Fractional distillation separates

Fractional distillation separates mixtures made of many multiple liquids from a solution.
liquids. In the laboratory, the solution is heated more than
once to different temperatures because each liquid has a ✓ Fractional distillation works because
different boiling point. An additional piece of equipment,
a fractionating column, helps separate each liquid. the liquids in the solution have
different boiling points.

Distilling crude oil 3. A thermometer records the different
Crude oil is usually separated in
industry (see pages 204–05), temperatures the mixture is heated to.
however it can also be done in
the laboratory. Steps 1–6 are 4. Hot gases cool at the top of the
repeated for each liquid that
is distilled. fractionating column.

Cool water is pumped around
the condenser tube to help the
gases to cool and condense.

Water in 5. Cool gases condense.

Water out

Liquids may evaporate at the same 6. Liquids are
time. Rounded edges in the tall
fractionating column provide a collected in flasks.
large surface area. This stops
liquids with higher boiling points They are swapped
than the liquid being separated on
the first try from reaching the top. for each liquid.

2. Liquid evaporates

into a gas

Fractionating column

1. Crude oil is heated.