A-Level Chemistry: Atomic Structure and Bonding

Atomic Structure

A-Level Chemistry begins with a deeper understanding of the atom than at GCSE. You must understand sub-atomic particles, electronic configuration, and how quantum mechanics shapes the periodic table.

Electronic Configuration

Electrons occupy shells, sub-shells (s, p, d, f) and orbitals. Fill in order: 1s, 2s, 2p, 3s, 3p, 4s, 3d... The 4s sub-shell fills before 3d but empties first when forming cations.

Types of Chemical Bonding

• Ionic: Transfer of electrons between metal and non-metal; giant ionic lattice structure

• Covalent: Sharing of electrons; simple molecular or giant covalent structure

• Metallic: Delocalised electrons in a lattice of positive ions

Bond Polarity and Electronegativity

The greater the difference in electronegativity, the more polar the bond. Use Pauling scale: F(4.0), O(3.5), N(3.0), Cl(3.0). Dipole moments in molecules determine solubility and boiling points.