This is the list made my Ms. Hoo. Please read yea =)

1. FORM 4 ‐ CHEMISTRY
NO TERMS/ STATEMENTS DEFINATION/ EXPLAINATION
1. Melting point The constant temperature at which ( solid changes into liquid ) at a
particular pressure.
2. Temperature remains constant: Reason:
i) Heating of naphthalene ( S & L ) i)Heat energy absorbed by the particles is used to overcome the force of
attraction between particles so that solid turn into liquid.
ii)Cooling of naphthalene ( L & S ) ii)Heat lost to the surroundings is exactly balanced by the heat energy
liberated as the particles attract one another to form solid.
3. Proton number The number of proton in the nucleus of an atom.
4. Nucleon number The total number of protons and neutrons in the nucleus of an atom.
5. Isotopes Atoms of same element with the same proton number but different
nucleon number/number of neutrons.
5. Valence electron Electrons found in the outermost occupied shell of an atom.
6. Mole The amount of substance that contains as many particles as the number of
atoms in exactly 12g of carbon‐12.
7. Molar mass ( g mol‐1) The mass of one mole of substance in grams.
8. Molar volume (dm3 mol‐1 ) The volume of 1 mole of gas.
9. Empirical formula The chemical formula that shows the simplest whole number ratio of
atoms of each element in the compound.
10. Molecular formula The chemical formula that shows the actual number of atoms of each
element in one molecule of the compound.
11. Group 1 /13 Reason: Because it has 1 valence electron / 3 valence electrons.
12. Period 3 Reason: Because it has 3 shells occupied with electrons.
13. Group 18 – elements inert/ Reason: It has 8 valence electrons/ achieve stable octet electron
chemically unreactive / arrangement. So, the atom cannot release electron , accept electron or
monoatomic. share electrons with other atoms.
14. Going down Group 1 ( alkali Reason:
metals), reactivity increase ‐Going down Group1, the atomic radius/ size increase.
‐The valence electron gets further away from nucleus.
‐ The force of attraction between nucleus and valence electron becomes
weaker.
‐Easier to donate the valence electron to achieve stable octet electron
arrangement.
15. Going down Group 17 ( halogen), Reason:
reactivity decrease. ‐Going down Group 17, the atomic radius/ size increase.
‐ The valence shell gets further away from nucleus.
‐ The strength of nucleus to attract one electron into the valence shell to
achieve stable octet electron arrangement decrease.
16. Across period, atomic size Reason:
decrease. ‐Across period, the proton number increase/ positive charge of nucleus
increase.
‐The force of attraction between nucleus and valence electrons becomes
stronger.
‐ The valence electrons are pulled closer to the nucleus.
17. Going down Group 17/ 18, Reason:
melting/ boiling point increase. ‐Going down the group, the atomic size increase.
‐The van der Waals force of attraction between molecus ( halogen)/ atom
( noble gas) become stronger.
‐More heat energy is required to overcome the force of attraction during
melting / boiling.

2. 18. Going down Group 1, melting/ Reason:
boiling point decrease. ‐ Going down the group, the atomic size increase.
‐The metallic bonding between the atoms in alkali metals become weaker.
‐Less heat energy is required to overcome the weaker metallic bonding
during melting/ boiling process.
19. Across period, electronegativity Reason:
increase. ‐Electronegativity is the strength of an atom to attract electron towards its
nucleus.
‐Across period, the atomic size decrease due to the increasing nuclei
attraction on the valence electron.
‐The strength of nucleus to attract electron increase.
20. Amphoteric oxide Oxide that shows both acidic and basic properties./ oxide that reacts with
both acid and alkali to produce salt and water.
21. Acid Chemical substance that ionize in water to produce hydrogen ion.
22. Base Chemical substance that react with acid to produce salt and water only.
23. Alkali Base that is soluble in water and ionize to produce hydroxide ion.
24. Strong / weak acid An acid that ionize completely/ partially in water to produce high/low
concentration of hydrogen ion.
25. Strong/weak alkali An alkali that ionize completely/ partially in water to produce high/low
concentration of hydroxide ion.
26. Monoprotic acid / diprotic acid Acid that produce I mol/ 2mol of hydrogen ion when 1 mole of acid
dissolve in water.
26. Standard solution A solution which its concentration is accurately known.
27. Neutralization Reaction between acid and base to form salt and water only.
28. Salt A compound formed when the hydrogen ion in an acid is replaced with
metal ion or ammonium ion.
29. Alloy A mixture of two or more elements with a certain fixed composition. The
major component in the mixture is a metal.
30. Polymer A long chain molecules made up of a large number of small repeating
identical unit.

3.
FORM 5 ‐ CHEMISTRY
NO TERMS/ STATEMENTS DEFINATION/ EXPLAINATION
1 Rate of reaction A measurement of the change in quantity of reactant or product
against time.
(Eg: Volume of hydrogen gas produced in 1 minute. )
2 Hydrocarbon Organic compounds that contain only carbon and hydrogen.
3 Saturated hydrocarbon Hydrocarbon that contains only single covalent bonds between
carbon atoms.
4 Unsaturated hydrocarbon Hydrocarbon that contains at least one double covalent bond
between carbon atoms.
5 Isomers Molecules with the same molecular formula, but different structural
formula.
6 Redox reaction Reaction where both oxidation and reduction occur at the same time.
7 Exothermic reaction Chemical reaction that gives out heat to the surroundings.
‐chemical energy in reactant change into heat energy.
‐temperature of surrounding increases
‐the reaction mixture and the container become hot.
8 Endothermic reaction Chemical reaction that absorb heat from the surroundings.
‐heat energy change is changed into chemical energy.
‐temperature of the surrounding increases.
‐the reacting mixture and the container become cold.
9 Heat of precipitation Heat released when one mole of precipitate (lead (II) sulphate )is
Eg: Pb(NO3)2 + K2SO4 PbSO4 + KNO3 formed from its ions ( Pb2+ ion and SO42‐ )in aqueous solution.
Ionic eqn: Pb2+ + SO42‐ PbSO4
10 Heat of displacement Heat released when one mole of metal ( copper ) is displaced from its
Eg: Zn + CuSO4 ZnSO4 + Cu solution ( copper(II) sulphate solution) by more electropositive metal
2+
Ionic eqn: Zn + Cu Zn2+ + Cu ( zinc ) .
11 Heat of neutralization Heat released when one mole of water is formed from neutralization
Eg: KOH + HNO3 KNO3 + H2O between acid (nitric acid )and alkali ( potassium hydroxide ).
Ionic eqn: H+ + OH‐ H2O
12 Heat of combustion Heat released when 1 mole of fuel ( ethanol ) is burnt completely in
Eg: C2H5OH + 3O2 2CO2 + 3 O2 excess oxygen.
13 Soap Sodium or potassium salt of fatty acid.
14 Saponification Reaction to prepare soap by hydrolyzing fats/oils in potassium
hydroxide or sodium hydroxide solution.
15 Detergent Cleaning agent that is not soap.
16 Soap only effective in soft water, but ‐Hard water contain high concentration of Ca2+ and Mg2+ ion.
detergent effective in both soft and ‐ Ca2+ ions and Mg2+ ions react with soap anions to form insoluble
hard water. Why? scum.
‐Formation of scum reduces the amount of soap for cleaning.
‐Detergent anions do not form insoluble scum with Ca2+ ions and Mg2+
ions.
‐Detergent can act as cleaning agent in hard water.