Chemistry SPM Practical Test

Chemistry Form 4 Definition List

Element Definition
Compound
Atom a substance consists of one type of atom
Molecule
Ion a substance consists two or more elements that are chemically
Melting point bonded (molecule or ions).
Freezing point smallest particle of an element that can participate in a chemical
Proton number reaction.
Nucleon number a group of two or more atoms which are chemically bonded
together.
Isotopes
a positively charged / negatively charged particle

The constant temperature when a substance changes from solid
state to become liquid at a specific pressure.
The constant temperature when a substance changes from liquid
state to become solid at a specific pressure.
The number of protons in the nucleus of an atom.
The total number of protons and neutrons in the nucleus of an
atom.
atoms of the same element with same proton number but different
nucleon numbers// same number of protons but different number
of neutrons

Standard
Representation of
an Atom

Electron Shows the nucleus and electron arrangement of an atom.
arrangement
Shows the number of protons and neutrons in the nucleus and
Atomic structure electron arrangement of an atom.

Natural The percentage of isotopes present in a natural sample of element.
abundance
Relative atomic the average mass of one atom of an element/((1/12) x the mass of
mass of an one carbon-12 atom)
element
Relative the average mass of one atom of an molecule/((1/12) x the mass
molecular mass of of one carbon-12 atom)
an element
A basic S.I unit used in measuring the amount of substances. One
Mole mole of substance contains as many particles as the number of
atoms in exactly 12 g of carbon -12 or 6.02 x 1023 particles.
The symbol of mole is mol.

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Avogadro The number of particles in one mole of a substance, which refers to
constant
the value of 6.02 x 1023 mol-1
Chemical formula
A representation of a chemical substance using alphabets to
Molecule formula represent the atoms and subscript numbers to show the number of
each type of atoms found in the elementary entities of the
Empirical formula substance.
Group (Periodic Chemical formula that shows the actual number of atoms of each
Table) element that are present in a molecule of the compound
Periods (Periodic Chemical formula that shows the simplest whole number ratio of
Table) atoms of each element in the compound
Valence electrons Vertical columns of elements in the Periodic Table Of Elements
Inert (similar chemical properties)
Alkali metal
Halogen Horizontal rows of elements in the Periodic Table Of Elements
Noble gas
Electrons found in the outermost shell of an atom.
Electronegativity Chemically unreactive

Acidic oxide An element in Group 1 of the Periodic Table

Amphoteric oxide An element in Group 17 of the Periodic Table

Basic oxide An element in Group 18 of the Periodic Table. Also known as inert
Metalloid/ Semi-
metallic Element gas.
Transition Element
A measurement of the strength of an atom in its molecule to
Chemical bond attract electrons towards its nucleus.
An oxide compound that can react with an alkali to form a salt
Ionic bond and water.
An oxide compound that exhibit both acidic and basic properties.
Ionic compound It is able to react with both acid and alkali to form a salt and water.
An oxide compound that can react with an acid to form a salt and
Covalent bond water.
A chemical element which has properties in between, or that are a
mixture of, those of metals and non-metals.
An element that is placed in Group 3 and 12 in the Periodic
Table of Elements.
A bond formed between atoms that transfer or share electrons to
form a compound
A chemical bond formed through the transfer of electrons
between a metal atom and a non-metal atom to achieve the
stable duplet or octet electron arrangement.
Consist of positive ions and negative ions which are held by strong
electrostatic forces of attraction.
A chemical bond formed when two or more non-metal atoms
share their electrons to achieve the stable duplet or octet electron
arrangement.

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Covalent Consists of neutral molecules which are held by weak
compound(simple intermolecular forces (Van der Waals).
molecular
structure) The attraction force between hydrogen atom, H bonded to highly
electronegative atoms, such as nitrogen, N, oxygen, O or fluorine, F
Hydrogen bond with nitrogen atoms, N, oxygen, O or fluorine, F in other molecules.
A type of covalent bond where the electron pair that is shared
Dative bond / comes from one atom only.
coordinate bond
Delocalised Electron that moves freely and is not owned by any atom nor ion.
electron
Volatile liquid A liquid with low boiling point that can easily be made to boil or
evaporate.
Alkali A base that is soluble in water/ A chemical substance which ionizes
in water to produce hydroxide ions, OH-.
Acid A chemical substance which ionizes in water to produce hydrogen
ions, H+ or hydroxonium ions, H3O+.
Basicity of Acids Refers to the number of hydrogen ions, H+ that can be produced
Monoprotic acid by an acid molecule that ionises in water.
Diprotic acid An acid that produces one H+ ion per acid molecule.
Triprotic acid An acid that produces two H+ ions per acid molecule.
pH scale An acid that produces three H+ ions per acid molecule.
pH value A scale with values from 0 to 14 which measures the degree of
Strong alkali acidity or alkalinity of an aqueous solution.
measure of the concentration of hydrogen ions, H+
Weak alkali ionizes (dissociates) completely in water to form hydroxide ions, OH-
of high concentration
Strong acid ionizes (dissociates) partially in water to form hydroxide ions, OH- of
low concentration
Weak acid ionizes (dissociates) completely in water to form hydrogen ions, H+
Concentration of of high concentration
a solution ionizes (dissociates) partially in water to form hydrogen ions, H+ of
Molarity of a low concentration
solution A measurement that shows the quantity of solute dissolved in a
Standard solution unit volume of solution, normally in 1 dm3 solution.
Neutralisation
The number of moles of solute found in 1 dm3 solution.
Titration
A solution with known concentration.
A reaction between an acid and an alkali (base) to produce salt
and water only.
A quantitative analysis method to determine the volume of acid
needed to completely neutralise a given volume of alkali and vice
versa.

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The point in a titration at which the acid-base indicator changes
colour.

End Point

Salt A compound formed when the hydrogen ion, H+ of an acid is
replaced by a metal ion or an ammonium ion, NH4+
Precipitation
reaction / Double A reaction used in the preparation of insoluble salts.
decomposition
reaction) A technique used to identify the cation and anion present in a salt
Qualitative by analysing its physical and chemical properties.
analysis of a salt The changes in the quantity of the reactant per unit time or the
changes in the quantity of product per unit time.
Rate of reaction

Catalyst A chemical substance that alter the rate of chemical reactions
Positive catalyst without undergoing any chemical changes at the end of the
Negative catalyst reaction.
Effective collision
Increases the rate of reaction & lower the activation energy.
Alloy
Decreases the rate of reaction & higher the activation energy

The collision where the total amount of energy of the colliding
(particles) is equal or greater than the activation energy and
collide in the correct orientation that results in a reaction and the
formation of products.

A mixture of two or more elements where the main
element is a metal.

Example: Bronze = 90% Copper + 10% Tin
Brass = 70% Copper + 30% Zinc

Composite A material made from combining two or more non-homogeneous
material substances. When combined, the composite material formed has
better properties than the original components (stronger, lighter,
resistant to electricity)
Example: Superconductors, Reinforced concrete, Photochromic
glass, fibre glass, optical fibre.

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Chemistry Form 5 Definition List

Redox reaction Chemical reactions where oxidation and reduction occur
simultaneously.
Oxidation A chemical reaction in which a substance gains oxygen, loses
reaction hydrogen, loses electrons or undergoes an increase in oxidation
number.
Reduction A chemical reaction in which a substance loses oxygen, gains
reaction hydrogen, gains electrons or undergoes a decrease in oxidation
number.
Oxidizing agent A substance that oxidise other substances and is reduced in a
redox reaction.
Reducing agent A substance that reduce other substances and is oxidised in a
redox reaction.
Oxidation number the charge of the elements in a compound if the transfer of
electrons occurs in an atom to form chemical bonds with other
Displacement of atoms.
metals A chemical reaction in which a more electropositive metal
Electropositivity displaces a less electropositive metal from its salt solution.
Displacement of
halogens The tendency of atoms to release electrons to form cations.

Standard A chemical reaction in which a more reactive halogen(at the top
electrode of Group 17) displace a less reactive halogen(at the bottom of
potentials, E0 Group 17) from its halide solution.
Electrochemical Potential difference produced in half cells under standard
Series conditions with a concentration of ion in an aqueous solution is 1.0
Anion mol dm−3 at 25 °C and pressure of 1 atm or 101 kPa and is coupled
Cation with standard hydrogen electrode.
A series of metal arrangement in the order of standard electrode
capacity, E0 from the most negative to the most positive.

A negatively charged particle.

A positively charged particle.

Anode The electrode where the oxidation reaction takes place.

Cathode The electrode where the reduction reaction takes place.

Shorthand representation of a chemical cell with the anode on the
left and the cathode on the right is separated by two vertical lines
representing a salt bridge or porous pot.

Cell notation

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Daniell cell Chemical cell consists of zinc, Zn metal electrodes and copper, Cu
metal electrodes dipped into their respective ionic salt solutions.
Electrolysis A process of decomposition of a compound in a molten state or an
aqueous solution to its constituent elements when electric current is
Electrolyte passed through it.
A substance in a molten state or an aqueous solution that can
Electroplating conduct electric currents and undergo chemical changes.
Reactivity series of The electrolysis process of coating the surface of a metal with thin
metal and even layer of another metal.
Metal corrosion A series of metal arrangement in an ascending order of metal
reactivity towards oxygen.
Rusting A redox reaction in which metal is oxidised spontaneously when a
metal atom releases an electron to form a metal ion.
Sacrificial A redox reaction in which there is an oxidation process of iron to
protection hydrated iron(III) oxide, Fe2O3.xH2O or rust.
A process of protection against the corrosion of metal. For
Galvanisation example, a more electropositive metal such as zinc acts as the
Carbon sacrificial metal(anode) and is corroded first, thus protecting iron
compound structures.
Hydrocarbon The process of coating of iron with a layer of zinc so that it is
Non hydrocarbon resistant to corrosion.
Saturated
hydrocarbon Compound that contain carbon as their constituent element.
Unsaturated
hydrocarbons Organic compounds containing only carbon and hydrogen.
Organic compounds containing carbon and hydrogen and other
Cracking elements, such as oxygen, nitrogen, phosphorus or halogens.
Hydrocarbons containing only single bonds between carbon
Homologous atoms.
series Hydrocarbons containing at least one double bond or triple bond
Functional group between carbon atoms.
The process whereby long chain hydrocarbons are broken down
into smaller molecules at high temperatures in the presence of a
catalyst.
A group of organic compounds which has the same functional
group and is represented by a general formula.

A group of atoms bonded to a molecule of an organic compound
that determines the chemical properties of homologous series.

Alkane A saturated hydrocarbon with carbon-carbon single bond (C―C)

Substitution with the general formula, , n=1,2,3…..
reaction
A chemical reaction that occurs when each hydrogen atom in an
alkane molecule is substituted one by one with halogen atoms,
until all the hydrogen atoms are substituted.

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Alkene An unsaturated hydrocarbon with at least one carbon-carbon

Addition reaction double bond ( C═C) with the general formula, , n=2,3...

Hydrogenation A chemical reaction that occurs when another atom is added to
each carbon atom at the double bond C═C to form a single
Hydration covalent bond C―C .
A process to turn an unsaturated compound(Alkene) into a
Alkyne saturated compound(Alkane) by reacting it with hydrogen gas at
180C in the presence of nickel/platinum as a catalyst.
Alcohol A process of addition of water to an alkene to produce alcohol.
The temperature used is 300°C and the pressure is about 60
Carboxylic acid atmospheres in the presence of phosphoric acid as a catalyst.

Ester An unsaturated hydrocarbon with at least one carbon-carbon
triple bond ( C≡C) with the general formula, CnH2n-2, n=2,3...
Esterification
An organic compound with the hydroxyl functional group, ―OH
Isomer
Endothermic and general formula, , n=1,2,3….
reaction
Exothermic An organic compound containing a carboxyl functional group,
reaction ―COOH with the general formula CnH2n+1COOH, n=0,1,2….
Heat of reaction, A sweet smelling compound produced from a reaction between
ΔH an alcohol and a carboxylic acid. General formula:
Heat of
precipitation Functional group: Carboxylate group
Heat of The reaction of alcohol with carboxylic acid with the presence of
displacement concentrated sulphuric acid to produce ester and water.
Heat of Molecules that have the same molecular formula but different
neutralisation structural formulae.
Heat of
combustion A chemical reaction that absorbs heat from the surroundings.
Thermochemical
equation A chemical reaction that releases heat to the surroundings.

Fuel value The heat change of one mole of reactant that reacts or one mole
of product that is formed. Unit = kJ mol-1
The heat change when 1 mole of a precipitate is formed from their
ions in an aqueous solution.
The heat change when 1 mole of a metal is displaced from its salt
solution by a more electropositive metal.
The heat change when one mole of water is formed from the
reaction between an acid and an alkali.
The heat change when one mole of a substance is completely
burnt in excess oxygen, O2
An equation consists of a balanced chemical equation and the
heat of reaction with a positive or negative sign.
The amount of heat energy released when one gram of the fuel is
completely burnt in excess of oxygen. ( Unit = kJ )

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Polymer A long chain molecule that is made from a combination of many
Monomer repeating basic units.
Polymerisation The basic unit of a polymer.
reaction
The monomer combination reaction to produce a polymer.
Vulcanization
A process of producing rubber that is more elastic and with better
Synthetic rubber quality through the production of (sulphur) cross-links between
Oil and Fats polymer chains.
A synthetic polymer that is elastic in nature or elastomer polymer.
Fatty acids esters produced through the reaction between fatty acids and
Soap glycerol (propan-1,2,3-triol).
are long-chain carboxylic acids (containing about 16 to 18 carbon
atoms).
A sodium or potassium fatty acid salt.

Detergent A sodium or potassium salts of sulphonic acids.
Saponification
process Hydrolysis of oils or fats in sodium hydroxide, NaOH or potassium
Soft water hydroxide, KOH solutions.
Water that does not contain calcium ions, Ca2+ or magnesium ions,
Hard water Mg2+ that dissolve in it.
Water that contains calcium, ions, Ca2+ or magnesium ions, Mg2+
Food addictive that dissolve in it.
A natural or synthetic ingredients added to food to prevent
Medicines damage or to improve the appearance, taste or texture.
Traditional Chemicals used to help with the treatment or prevention of
medicine diseases.
Cosmetics Obtained from herbal plants or animals and are not chemically
processed.
Nanoscience Materials or products that are used externally to cleanse, protect or
enhance one’s appearances.
Nanotechnology A study on processing of substances at nanoscale that are
between 1 nanometre to 100 nanometres.
A development of substances or gadgets using the properties of
nanoparticles.

Graphene One of the carbon allotropes, other than diamond and graphite.

Green Technology A technology or application developed to minimise the negative
effects of harmful human activities.

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Form 4

Operational Definition Chapter

Reactivity of Group 1 metal with water 4: Group 1
An alkali metal that reacts more vigorously and rapidly with water Elements
is a more reactive metal.

Reaction of halogens with water

1. When blue litmus paper turns red, the solution formed shows 4: Group 17
acidic property. Elements

2. When blue litmus paper turns white, the solution formed shows

bleaching property.

Reaction of halogens with iron 4: Group 17
The appearance of a brown solid shows formation of iron(III) Elements
halides.

Properties of Oxides of elements in Period 3

1. Oxide that dissolves in water to form solution with pH less than 7 is

acidic

2. Oxide that dissolves in water to form solution with pH more than

7 is alkaline. 4 : Period 3

3. Oxide that can dissolve in an acid exhibits basic properties.

4. Oxide that can dissolve in an alkali exhibits acidic properties.

5. Oxide that can dissolve in both acid and alkali exhibits

amphoteric properties

Electrical Conductivity (Ionic and covalent compound)

Electrical conductivity is defined operationally as the ammeter 6 : Electrolyte and

reading which is greater than zero/ the ammeter shows a reading/ Non-electrolyte

ammeter needle deflects.

Effect of specifics of electrodes on the electrolytic process of an 6: Electrolysis of
electrolysis Aqueous Solution
Differences in observation at the anode indicate different types of

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products formed

Production of electricity from chemical reaction

When an electric current is produced, the voltmeter shows a 6: Voltaic Cells

reading/ voltmeter needle deflects.

6: Electrochemical
Displacement reaction occurs when there is a deposition of metal.

Series

Blue litmus paper turning red indicates acidic property. 7: Acids and Bases

Hardness of alloy 9: Alloys
If the dent is smaller, then the material is harder.

Rate of rusting of iron 9: Alloys(Rusting)
The more blue the colour, the higher is the rate of rusting.

Form 5

Operational Definition Chapter

Effect of size of reactants 1: Factors that

The rate of reaction is measured by how fast the volume of carbon affect Rate of

dioxide, CO2 increases. Reaction

Effect of concentration / temperature of solution 1: Factors that
The rate of reaction is the time taken for the cross 'X' to disappear" affect Rate of
from sight/ is measured by how fast the 'X' is hidden by the yellow Reaction
precipitate.

Effect of temperature of solution 1: Factors that
The rate of reaction is the time taken for the cross 'X' to disappear" affect Rate of
from sight when the sodium thiosulphate solution is heated to Reaction
various temperatures and then reacted with dilute sulphuric acid

Elasticity of natural rubber and vulcanized rubber 2: Rubber
Elasticity of rubber is the difference between the length after the

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weight used to stretch it is removed, l2 and the original length l1.

Coagulation of latex 2. Rubber
When acid is added to latex, white solid is formed.

Transfer of electron at a distance (Using U-tube) 3: Redox
The change in colour of the solutions at arm X and arm Y shows the Reactions
transfer of electrons.

Reactivity of metals

The brightness of flame when the metal powder is heated & 3: Redox
burned with oxygen gas. Reactions
The brighter the flame, the more reactive the metal towards

oxygen

Effect of other metals on rusting

Rusting of iron is the formation of blue colourisation when iron is in 3: Rusting as a

contact with a less electropositive metal/ Redox Reaction

Presence of blue colouration in agar-agar.

Heat of combustion of alcohols 4:
Heat of combustion of alcohols is the amount of heat energy Thermochemistry
released when one mole of the alcohol is burnt in excess oxygen.

Effectiveness of cleaning action of Soap and Detergent

The ability of a cleaning agent to remove oily stains on a cloth

indicates that the cleaning agent is effective.

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SPM Form 4 – Terminology and Concepts: Chemical Formulae and Equations

1. Relative atomic mass, Ar is the atomic mass of an atom when compared to a
standard atom

2. Standard atom:

Hydrogen scale: hydrogen is the lightest atom of all and the mass of one hydrogen
atom was assigned 1 unit.
Weakness of Hydrogen scale:
 not too many elements can react readily with hydrogen,
 the reactive masses of some elements were not accurate,
 hydrogen exists as a gas at room temperature and
 has a number of isotopes with different masses.

Oxygen scale: chose as the standard atom to compare the masses of atoms
Weakness of Oxygen scale:
 the existence of three isotopes of oxygen were discovered,
 natural oxygen (containing all the three isotopes) as the standard (Chemist) and
 used the isotopes oxygen-16 as the standard (Physicists).

Carbon scale: standard atom of comparison internationally.
 a carbon-12 atom is 12 times heavier than an atom of hydrogen,
 used as the reference standard in mass spectrometers,
 exists as a solid at room temperature,
 most abundant carbon isotope, happening about 98.89% and
 carbon-12 is close to the agreement based on oxygen.

3. Relative molecular mass, Mr of a substances is the average mass of a molecule
(two or more atoms) of the substances when compared 1/12 with of the mass of a
carbon-12 atom.

4. Relative formula mass, Fr is for ionic compound which is calculated by adding up
the relative atomic masses of all the atoms.
Example:
 Relative atomic mass, Ar of helium = 4
 Relative molecular mass, Mr of CO2 = 12 + 2(16) = 44
 Relative formula mass, Fr of NaCl = 23 + 35.5 = 58.5
 Relative formula mass, Na2CO3·10H2O = 2(23) + 12 + 3(16) + 10 [2(1) + 16] = 286

5. Avogadro constant / Avogadro’s number is 6.02 x 1023

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6. Atomic substances
 Elements – all the particles are atoms.
 Example: zinc (Zn), sodium (Na), aluminium (Al) and all noble gases, argon (Ar),
helium (He) and neon (Ne).
 RAM (Relative Atomic Mass) of Na = 23

7. Molecular substances
 Covalent compounds – the particles are molecules.
 Example: carbon dioxide (CO2), water (H2O) and non-metal elements, iodine (I2),
nitrogen (N2) and oxygen (O2).
 RMM (Relative Molecular Mass) of I2 = 127 + 127 = 254

8. Ionic substances
 Ionic compounds – the particles are ions.
 Example: sodium chloride (NaCl), hydrochloric acid (HCl) and potassium iodide
(KI).
 RFM (Relative Formula Mass) of HCl = 1 + 35.5 = 36.5

9. Avogadro’s Law / Gas Law states that equal volumes of all gases contain the same
number of molecules under the same temperature and pressure.
 Example: equal volumes of molecular hydrogen and nitrogen would contain the
same number of molecules under the same temperature and pressure.

10. Volume of gas (dm3) = Number of moles of gas x Molar volume

11. Room temperature and pressure (r.t.p.) = 24 dm3 mol-1 (25°C and 1 atm)
 Example: What is the volume of 5.0 mol helium gas at s.t.p.?
 Volume of gas = Number of moles x Molar gas volume
= 5.0 mol x 24 dm3 mol-1
= 120 dm3

12. Standard temperature and pressure (s.t.p.) = 22.4 dm3 mol-1 (0°C and 1 atm)
 Example: What is the volume of 5.0 mol helium gas at s.t.p.?
 Volume of gas = Number of moles x Molar gas volume
= 5.0 mol x 22.4 dm3 mol-1
= 112 dm3

13. Mass (g) = Number of moles x Molar mass

14. Number of particles = Number of moles x Avogadro constant

15. Volume (dm3) = Number of moles x Molar volume

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Empirical and Molecular Formulae

1. Empirical formula – chemical formula that shows the simplest whole number ratio of

atoms of each element in the compound

2. Molecular formula - chemical formula that shows the actual number of atoms of

each element that are present in a molecule of the compound.

3. Molecular formula = (empirical formula)n n , n is a positive number
Compound Molecular formula Empirical formula

Carbon dioxide CO2 1 (CO2) = CO2

Ethane CH3 2 (CH3)2 = C2H6

Propene CH2 3 (CH2)3 = C3H6

Glucose CH2O 6 (CH2O)6 = C6H12O6

Quinine C10H12NO 2 C20H24N2O2

4. Chemical formulae for covalent compounds.

Name Chemical formula Number of each element

Nitrogen gas N2 2 nitrogen atoms

Oxygen gas O2 2 oxygen atoms

Ammonia NH3 1 nitrogen atom and 3 hydrogen atoms

Water H2O 2 hydrogen atoms and 1 oxygen atom

5. Cations are positively-charged ions.

Charge Cations Formula Charge Cations Formula
+1 Ammonium ion NH4+ +2 * Iron(II) ion Fe2+
+1 * Copper(I) ion Cu+ +2 * Lead(II) ion Pb2+
+1 Hydrogen ion H+ +2 Magnesium ion Mg2+
+1 Li+ +2 * Manganese(II) ion Mn2+
+1 * Lithium ion Ni+ +2 Nickel(II) ion Ni2+
+1 Nickel(I) ion K+ +2 * Tin(II) ion Sn2+
+1 Potassium ion Ag+ +2 Zn2+
Zinc ion
Silver ion

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+1 Sodium ion Na+ +3 Aluminium ion Al3+

+2 Barium ion Ba2+ +3 * Chromium(III) ion Cr3+

+2 Calcium ion Ca2+ +3 * Iron(III) ion Fe3+

+2 * Copper(II) ion Cu2+ +4 * Lead(IV) ion Pb4+

+4 * Tin(IV) ion Sn4+

* refer to the Roman numerals

6. Anions are negatively-charged ions.

Charge Anions Formula Charge Anions Formula
O2-
-1 Bromide ion Br- -2 Oxide ion
CO32-
-1 Chloride ion Cl- -2 Carbonate ion CrO42-
Cr2O72-
-1 Chlorate(V) ion ClO3- -2 Chromate(VI) ion
S2-
-1 Ethanoate ion CH3COO- -2 Dichromate(VI) ion SO42-
SO32-
-1 Fluoride ion F- -2 Sulphide ion S2O32-
N3-
-1 Hydride ion H- -2 Sulphate ion PO43-
PO33-
-1 Hydroxide ion OH- -2 Sulphite ion

-1 Iodide ion I- -2 Thiosulphate ion

-1 Manganate(VII) ion MnO4- -3 Nitride ion

-1 Nitrate ion NO3- -3 Phosphate ion

-1 Nitrite ion NO2- -3 Phosphite ion

7. Chemical formulae for ionic compounds

Name Chemical Number of cation Number of anion
formula
Zinc chloride ZnCl2 1 Zn2+ 2 Cl-
Copper(II) sulphate CuSO4 2 Cu2+ 2 SO42-
Aluminium sulphate Al2(SO4)3 2 Al3+ 3 SO42-

8. Meaning of prefixes

Prefix Meaning Prefix Meaning
Mono- 1 Hexa- 6
2 Hepta- 7
Di- 3 Octa- 8
Tri- 4 Nona- 9
Tetra- 5 Deca- 10
Penta-

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9. Naming of chemical (non-metal) compounds with Greek numerical prefixes.

Non-metal compound Chemical formula
Carbon monoxide CO
Carbon dioxide CO2
Sulphur dioxide SO2
Sulphur trioxide SO3

Carbon tetrachloride CCl4
(tetrachloromethane)

Chemical Equation

1. Importance of chemical equation:
The types of reactants; the physical conditions; the quantity of reactants and
products and stated in moles.
nA + nB → pC + pD

2. Reactants are written in the left side of the reaction and products are written in the
right side of the reaction.
 Example 1:
Word equation: Sodium hydroxide + sulphuric acid → sodium sulphate + water
Chemical equation: NaOH + H2SO4 → Na2SO4 + H2O
Balancing equation: 2NaOH + H2SO4 → Na2SO4 + 2H2O
Complete chemical equation: 2NaOH + H2SO4 → Na2SO4 + 2H2O
 Example 2:
Word equation: Aluminium + copper(II) oxide → aluminium(III) oxide + copper
Chemical equation: Al + CuO → Al2O3 + Cu
Balancing equation: 2Al + 3CuO →Al2O3 + 3Cu
Complete chemical equation: 2Al + 3CuO → Al2O3 + 3Cu
 Example 3:
Word equation: Nitrogen + hydrogen ⇋ ammonia
Chemical equation: N2 + H2 ⇋ NH3
Balancing equation: N2 + 3H2 ⇋ 2NH3
Complete chemical equation: N2 + 3H2 ⇋ 2NH3

3. Information obtainable from chemical equations.
 i) mass of reactants
 ii) volume of reacting gas
 iii) mass of products formed

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 iv) volume of gas produced
Example:
2 g of lead (II) nitrate solution is added to excess of potassium iodide solution.
How many molecules of potassium nitrate will be formed?
[Relative atomic mass: N, 14; O, 16; K, 39; I, 127; Pb, 207; Avogadro's constant:
6.02 x 1023 mol-1]

Step 1: Write a complete chemical equation.
Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq)
From the equation, 1 mole of Pb(NO3)2 reacts with 2 moles of KI formed 1
mole PbI2 of and 2 moles of KNO3.

Step 2: Convert to moles.
No. of moles of Pb(NO3)2
= Mass of Pb(NO3)2 / Relative molecular mass
= 2 / [207 + 2(14 + 3 x 16)]
= 6.04 x 10-3 mol

Step 3: Ratio of moles.
Number of moles of KNO3/ Number of moles of Pb(NO3)2
= 2/1
Number of moles of KNO3
= (2 x 6.04 x 10-3) / 1
= 12.08 x 10-3 mol

Step 4: Convert to the number of molecules of potassium nitrate.
Number of molecules of KNO3
= 12.08 x 10-3 x 6.02 x 1023

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Volume(dm3 ) Molar volume
MolarVolume 6.02 x 1023

6.02 x 1023

Preservative A substance added to food to prevent or delay the growth of
Antioxidant bacteria or fungi to make the food last longer.
A substance used to slow down the deterioration of food caused
by oxygen from the air//substance added to prevent oxidation
that causes rancid fats and brown fruits

.
Flavouring is a substance used to improve the taste of food and restore taste loss
because of processing.
Thickener is a substance used to thicken foods and give the food a firm, smooth and
uniform texture.
Food dye is a substance used to add or restore the colour in food.
Stabiliser is a substance which helps to prevent an emulsion from separating out.
Medicine is a substance used to prevent or cure disease or to relieve pain.
Analgesic is a medicine used to relieve pain without causing numbness or affecting
consciousness.
Antibiotic is a medicine used to kill or slow down the growth of bacteria.

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Psychotherapeutic medicine is a medicine used to alter abnormal thinking, feelings or
behaviours.
Antidepressant is a medicine used to calm down a person and thus reduce tension and
anxiety.
Antipsychotic is a medicine used to treat psychiatric illness.
Stimulant is a medicine which activates the level of activity arousal or alertness of the
central nervous system to reduce fatigue and elevate mood in most people.

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