Chemistry IGCSE Revision
Comprehensive Questions and
Solutions Graded A+
Ionic Bonding - Answer: Between a metal and a non-metal
1) soluble in water - polar water molecules are attracted to the giant 3D crystal lattice and break
it apart
2) conduct electricity when molten - when molten, the bonds have broken and the electrons are
free to move and carry charge
3) normally solids at room temperature - ions held in a fixed position by strong bonds
4) higher melting and boiling points - strong ionic bonds in a 3D crystal lattice that take much
energy to break
Covalent Bonding - Answer: Between 2 non-metals
1) insoluble in water
2) brittle solids, liquids or gases at room temperature
3) don't conduct electricity when molten
4) lower melting and boiling points - molecules are held together by weak intermolecular forces
that are easy to break
Diatomic Gases: a nitrogen molecule has a triple bond, a carbon dioxide molecule has two
double bonds, an oxygen molecule has two double bonds.
Cation - Answer: Positive Ion
, Anion - Answer: Negative Ion
Metallic Bonding - Answer: An array of positive ions in a sea of delocalised electrons. Most
metals are hard and have high melting points. Good conductors of heat. Malleable and ductile.
Solids - Answer: Particles are closely packed in a regular structure. The only movement the
particles have is vibration.
Liquid - Answer: Particles are still mainly touching but some gaps have appeared. Liquids are
usually less dense that the solid.
Gas - Answer: Particles are much further apart and there are almost no forces of attraction
between them.
Changes of State - Answer: Solid --> Liquid - Melting
Liquid --> Solid - Freezing
Liquid --> Gas - Boiling
Gas --> Liquid - Condensing
Solid --> Gas and Gas --> Solid - Sublimation
Diffusion - Answer: The spreading out of particles in a gas or a liquid. The lighter the particles,
the faster they diffuse. This is demonstrated by the experiment with cotton wool soaked in
ammonia solution at one end of a tube and cotton wool soaked in HCl at the other end. The
white cloud of ammonium chloride forms closer to the hydrochloric end. Also to speed up
diffusion, you can stir a liquid or heat up the liquid or gas.
Isotope - Answer: Atoms that have the same atomic number but different mass numbers. They
have the same number of protons but a different number of neutrons. Number of electrons =
number of protons.
Comprehensive Questions and
Solutions Graded A+
Ionic Bonding - Answer: Between a metal and a non-metal
1) soluble in water - polar water molecules are attracted to the giant 3D crystal lattice and break
it apart
2) conduct electricity when molten - when molten, the bonds have broken and the electrons are
free to move and carry charge
3) normally solids at room temperature - ions held in a fixed position by strong bonds
4) higher melting and boiling points - strong ionic bonds in a 3D crystal lattice that take much
energy to break
Covalent Bonding - Answer: Between 2 non-metals
1) insoluble in water
2) brittle solids, liquids or gases at room temperature
3) don't conduct electricity when molten
4) lower melting and boiling points - molecules are held together by weak intermolecular forces
that are easy to break
Diatomic Gases: a nitrogen molecule has a triple bond, a carbon dioxide molecule has two
double bonds, an oxygen molecule has two double bonds.
Cation - Answer: Positive Ion
, Anion - Answer: Negative Ion
Metallic Bonding - Answer: An array of positive ions in a sea of delocalised electrons. Most
metals are hard and have high melting points. Good conductors of heat. Malleable and ductile.
Solids - Answer: Particles are closely packed in a regular structure. The only movement the
particles have is vibration.
Liquid - Answer: Particles are still mainly touching but some gaps have appeared. Liquids are
usually less dense that the solid.
Gas - Answer: Particles are much further apart and there are almost no forces of attraction
between them.
Changes of State - Answer: Solid --> Liquid - Melting
Liquid --> Solid - Freezing
Liquid --> Gas - Boiling
Gas --> Liquid - Condensing
Solid --> Gas and Gas --> Solid - Sublimation
Diffusion - Answer: The spreading out of particles in a gas or a liquid. The lighter the particles,
the faster they diffuse. This is demonstrated by the experiment with cotton wool soaked in
ammonia solution at one end of a tube and cotton wool soaked in HCl at the other end. The
white cloud of ammonium chloride forms closer to the hydrochloric end. Also to speed up
diffusion, you can stir a liquid or heat up the liquid or gas.
Isotope - Answer: Atoms that have the same atomic number but different mass numbers. They
have the same number of protons but a different number of neutrons. Number of electrons =
number of protons.
