Melting and Boiling Point of Elements in Period 3

1. Metallic Structure

1.1. Melting and boiling point increase from Na to Al

1.2. Across the period, strength of metallic bonding is proportional to the number of delocalized electrons.

1.3. The more the valence electrons, the stronger the metallic bonding

1.4. Sodium (Na), Magnesium (Mg), Aluminium (Al)

2. Simple Molecular Structure

2.1. Melting and boiling point from P to Ar

2.2. Elements exist as monoatom

2.3. Covalent bond between atoms is very strong but Van der Waals force is very weak

2.4. Phosphorus (P), Sulphur (S), Chlorine (Cl), Argon (Ar)

3. Gigantic Covalent Structure

3.1. Melting and boiling point is very high

3.2. Covalently bonded to other atoms at neighbouring lattice sites

3.3. Strong attractions between covalently bonded atoms, thus lots of chemical energy needed to break the covalent bonding

3.4. Silicon (Si)