Chemical bonding occurs for atoms to obtain the same number of valence electrons as a noble gas.

Helium has 2 valence electrons (duplet).
All other noble gases have 8 valence electrons (octet).

A positively or negatively charged particle when an atom loses or gains electrons respectively, to obtain the noble gas electronic configuration.

Metallic elements lose electrons to form positively charged cations. Non-metallic elements gain electrons to form negatively charged anions.

An electrically neutral particle made up of two or more atoms joined together by covalent bonds.

Atoms combine chemically by sharing electrons to form molecules.

A huge 3D network of atoms held by strong covalent bonds in silicon dioxide, diamond and graphite.

1. High melting and boiling points
2. Insoluble in water and organic solvent
3. Do not conduct electricity (except graphite)
4. Diamond is hard but graphite is slippery

A huge 3D network of oppositely charged ions held by strong ionic bonds.

1. High melting and boiling points
2. Soluble in water but insoluble in organic solvent
3. Conducts electricity when aqueous or molten only

A huge 3D network of metal cations in a sea of delocalised electrons held by strong metallic bond.

1. High melting and boiling points
2. Insoluble in water and organic solvent
3. Conducts electricity in all physical states
4. Malleable and ductile

A structure made up of discrete simple molecules held together by weak intermolecular forces of attraction.

1. Low melting and boiling points
2. Insoluble in water but soluble in organic solvent
3. Do not conduct electricity in all states

The attraction between different molecules, much weaker than the covalent bond within a molecule.

Intermolecular forces of attraction are also found between graphite layers.

Higher melting and boiling points when bonds between particles are stronger, which require more energy to overcome.

1. Intermolecular forces of attraction are much weaker
2. For ionic bond, its strength is greater when the charge is larger

A substance can conduct electricity if it has mobile ions or delocalised electrons that are free-moving.

Giant metallic: delocalised electrons
Graphite: free-moving electrons
Giant ionic: mobile ions when aqueous or molten

A substance can dissolve when bonds between particles are overcome by interactions between solute and solvent.

Soluble in water: ionic compounds, sugar, alcohol
Soluble in organic solvent: simple molecules

A malleable material can be hammered easily into different shapes, while a ductile one can be stretched into thin wires.

Metals are ductile and malleable as layers of metal ions can slide over each other easily through the sea of electrons, without disrupting the metallic bonding.