module chapter 2 kssm chemistry

Chemistry..think beyond what you see [email protected]

Chapter 2 Matter and the
atomic structure

2.1 Basic Concepts of Matter
2.2 The Development of Atomic Model
2.3 Atomic Structure
2.4 Isotopes and Its Uses

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2.1 Basic Concepts of Matter

2.1.1 Describe matter briefly three types of particles:
•atom
• matter is something that has mass and occupies space. •ion
• matter consists of particles that are tiny and discrete •molecule
• matter exist in three states: solid, liquid and gas.

Matter

element compound

atom molecule molecule ion

2.1.2 explain the changes in the states of matter

• change in state of matter is caused by Heating and Cooling
• Heating (absorb energy): melting, boiling, evaporation, sublimation
• Cooling (release energy): freezing, condensation, deposition

sublimation

melting boiling/
evaporation

State

arrangement particles are particles are particles are far
closely packed closely packed apart
in an orderly but not in an
manner orderly manner

kinetic energy low higher than very high
solid weak
force of strong
attraction strong but less
than solid state

freezing condensation
deposition

2.1.3 Determine the melting and boiling point

• Melting point is the constant temperature when a substance changes from solid state
to become liquid at a specific pressure

• Freezing point is the constant temperature when a substance changes from liquid
state to become solid at a specific pressure
Temperature (oC)

Melting • melting occurs D
point • no increase in temoerature from
• temperature increases
A B to C because heat energy from C to D
absorbed by the particles is
used to overcome the attraction • exist in liquid state
force between the particles until • when heated, the
solid changes to liquid
partcles absorb heat
BC energy and move
faster
• temperature increases from A to B
• exist in solid state
• when heated, the partcles absorb

heat energy and vibrate faster
because kinetic energy increases

heating curve of naphthalene, C10H8 Time(min)

Temperature (oC)

• temperature decreases from E to F

• exist in liquid state • temperaturedecreases
from G to H
E • when cooled, the partcles release
heat energy and move slower due • exist in solid state
• when cooled, the
to the lose of kinetic energy
partcles released heat
Freezing F energy and vibrate
point slower
• freezing occurs
• no decrease in temoerature from G

F to G because heat energy that H
is lost to the surroundings is
balanced by heat released when
the particles attract each other
to form solid

cooling curve of naphthalene, C10H8 Time(min)

Exercise 2.1

1. State the types of particles that exist in copper wire, table salt and oxygen gas.

(3 marks)

2. Azril dries his cloth under the Sun.
a) name the process involved during cloth drying

(1 mark)

b) state the changes in the movement of water particles when cloth is dried.
(1 mark)

3. Aimi buy an ice cream from a shop. When she arrives at home, the ice cream
become soft. She put the ice cream in the freezer for half an hour before enjoy it.
a) name the process involve when the ice cream placed in the freezer for half an hour
(1 mark)

b) explain the changes in kinetic energy of the particles and forces of attraction in ice
cream in the freezer
(2 marks)

4. P is a substance that has a melting point of 53 oC and a boiling point of 179 oC.
a) sketch a gfaph of temperature againts time when substance P is heated from 30 oC
to 95 oC.

(2 marks)
b) when substance P is cooled, the temperature decreases and becomes constant at

one stage and then decreases again.
Predict the constant temperature and explain why the temperature is constant at that
stage.

(3 marks)









[SPM 2019-21] Diagram 3 shows the cooling curve of liquid X.
Rajah 3 menunjukkan lengkung penyejukkan bagi cecair X.

Which of the following statement is correct?
Antara penyataan berikut yang manakah betul?

A. All particles vibrate at t1
Semua zarah bergetar pada t1

B. From t1 to t2 particles do not release heat energy.
Dari t1 hingga t2 zarah-zarah tidak membebaskan tenaga haba

C. From t1 to t2 particles particles are packed closely together
Dari t1 hingga t2 zarah-zarah tersusun rapat dengan mampat.

D. Forces of attraction between particles is overcome at t2
Daya tarikan antara zarah-zarah diatasi pada t2.

2.2 The Development of the Atomic Model

2.2.1 state the subatomic particles in atoms of various elements

23 Protons: 11
Electrons: 11
Na11 Neutrons: 12

Element symbol relative protons electrons neutrons
atomic mass
Magnesium 12 12 12
Fluorine Mg 24 99 10
Potassium 19 19 20
Oxygen F 19 88 8
Argon 18 18 22
K 39

O 16

Ar 40

2.2.2 compare and contrast the relative mass and relative charge
of proton, electron and neutron

proton netron electron

symbol symbol symbol
p n e

relative relative relative
charge = +1 charge = 0 charge = -1

relative mass relative mass relative mass
= 1 = 1 = 1 / 1840

2.2.3 Sequence the atomic models based on atomic models of Dalton,
Thomson, Rutherford, Bohr and Chadwick

Dalton's Atomic Model

• an atom is the smallest spherical body that

cannot be created, destroyed nor divided

further Dalton= atom

Thomson's Atomic Model
• discovered electrons
• atom is positive charge sphere

Thomson = electrons

Rutherfords's Atomic Model
• discovered protons in nucleus
• atomic mass concentrated in nucleus
• electrons move outside nucleus

Rutherford = protons

Bohr's Atomic Model
• discovered shells
• electron move in shells around nucleus

Bohr = shells

Chadwick's Atomic Model
• discovered neutrons
• neutrons contribute half of atomic mass

Chadwick = neutrons

Dalton atom Thomson electron Rutherford proton Bohr shell Chadwick neutron

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Exercise 2.2

1. State the subatomic particles found in the nucleus of Beryllium.

(2 marks)

2. Electrons move around the nucleus in shells. Nucleus of ana om consists of protons
and neutrons. Based on this information, which scientist identified it?

(1 mark)

3. Determine the number of electron and neutrons in in the table below

Particle

12 C 14 C
6 6

number of
electron

number of neutron

4. Which scientist discovered protons? (4 marks)
5. Which scientist discovered electron move around the shells? (1 mark)
(1 mark)





2.3 Atomic Structure

2.3.1 Define proton number and nucleon number

proton number is the number of proton in the nucleus of an atom

Nucleon number is the total number of protons and neutrons in the
nucleus of an atom

2.3.2 Determine the nucleon number, proton number and number of
electron in an atom

An ATOM is NEUTRAL when the number of electrons is the same
with number of protons

example 1:

A Potassium atom has 19 protons and 20 neutrons. What are the
proton number and nucleon number of potasium atom?

solution,

Proton number = number of proton
= 19

Nucleon number = proton number + number of neutrons
= 19 + 20
= 39

example 2:

The nucleon number of phosphorus is 31. a phosphorus atom has 15
protons. how many neutrons are there in phosphorus atom?

solution,

Number of neutron = number of nucleon - number of protons
= 31 - 15
= 16

2.3.3 write standard representation of atom

nucleon Na23 symbol of
number element
11
proton
number

Comparison among number of protons, netrons and electrons
between ATOM and ION

type of particle Magnesium atom Magnesium ion
Mg Mg2+

number proton 12 12

number of neutron 12 12

number of electron 12 10

2.3.4 construct an atomic structure diagram and electron arrangement

proton number of fluorine atom is 9. Thus the electron
valence
arrangement of fluorine atom is 2. 7
electrons

atomic structure shows the number of Electron arrangement shos the nucleus
protons and neutrons in the nucleus and and electron arrangement of an atom
the electron arrangement of an atom

10 n F
9p

2.7 2.7







[SPM 18-20] Diagram 4 shows the standard representation of fluorine atom.
Rajah 4 menunjukkan perwakilan piawai bagi atom florin.

What is the number of valence electron of the atom?
apakah bilangan elektron valens bagi atom tersebut?
A. 7
B. 8
C. 9
D. 10

2.4 Isotopes and Its Uses

2.4.1 Deduce the meaning of isotopes

isotopes are atoms of the same element with the same number of protons but different
number of neutrons.

isotope atomic number of number of number of
standard protons neutrons electrons
chlorine-35 representation
chlorine-37 17 18 17
35 Cl
17 20 17
17

37 Cl

17

2.4.2 calculate the relative atomic mass of isotopes

• relative atomic mass of isotopes depend on the natural abundance of isotopes in a
sample

• Natural abundance the percentage of isotopes present in a natural sample of elements.
• the relative atomic mas can be calculate using formula:

relative atomic mass = ∑ (% isotope X mass of isotope)
100

excercise
1. Define isotopes

(2 marks)

2. Based on below, which atoms are isotopes?. explain your answer.

element npurmotboenr nnuumcleboenr
W 6 12
X 6 13
Y 11 23

Z 12 24

(3 marks)
3. Magnesium exist naturally as three isotopes, which are 79.0 % of 24Mg, 10.0 % 0f 25Mg

and 11.0% of 26Mg. Calculate the relative atomic mass of magnesium.

(2 marks)

2.4.3 justify the usage of isotopes in various fields

medicine Iodine-131
• treatment of thyroid disorder s as
cobalt-60
• in radiotheraphy to kill cancer hyperthyroidism and thyroid
cancer
cells withour surgery
• sterilising surgical tools

Carbon-14 Archaeology
• estimation of artifacts or fossils'
Lead-210
age • in determineing the age of sand

and earth layers up to 80 years

Agriculture Nuclear

Phosphorus-32 Uranium-235
• to study plant metabolism • generating electricity through

nuclear power generator

Industry Engineering

Hydrogen-3 Sodium-24
• as a detector to study sewage and • ditecting leakage in underground

liquid waste pipes



[SPM 19-14] Diagram 1 shows a woman suffering from a disease.
Rajah1 menunjukkan seorang wanita yang menghidapi sejenis penyakit.

Which of the following is used to treat the disease?
Antara yang berikut, yang manakah digunakan untuk merawat penyakit tersebut?
A . Cobalt-60
B. Iodine -131
C. Carbon-12
D. Uranium-236

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Answer this!!! (from text book chemistry form 4)