AQA Chem · 3.1.3 p.1
bonding
Ionic
Metal + non-metal : electrons transferred to give
Cl⁻ big
full outer shells
Ions attract by electrostatic forces → giant ionic Na⁺ smal
lattice
NaCl: Na loses 1 e⁻ (Na⁺), Cl gains 1 e⁻ (Cl⁻)
SO₄²⁻ sulfate OH⁻ hydroxide NO₃⁻ nitrate CO₃²⁻ carbonate NH₄⁺ ammonium
•• ××
Covalent
Two non-metals share electron pairs for a full outer •• Cl × Cl ××
shell •
Multiple pairs shared → double/triple bonds •• ××
Dot-and-cross diagrams; a straight line = one bond
H
Dative (coordinate) lone pair
Both shared electrons come from one atom (a lone
pair ), drawn as an arrow H N H⁺
NH₃ + H⁺ → NH₄⁺ NH₄⁺
Once formed, it acts as a normal covalent bond H
Metallic + + + + +
Lattice of positive ions in a sea of delocalised + + + + +
electrons ; strong electrostatic attraction + + + + +
Higher ion charge (more electrons released) → sea of delocalised e⁻
+ + + + +
stronger
Bigger ions (e.g. Ba) → weaker (greater radius)
bonding ·
bonding
Ionic
Metal + non-metal : electrons transferred to give
Cl⁻ big
full outer shells
Ions attract by electrostatic forces → giant ionic Na⁺ smal
lattice
NaCl: Na loses 1 e⁻ (Na⁺), Cl gains 1 e⁻ (Cl⁻)
SO₄²⁻ sulfate OH⁻ hydroxide NO₃⁻ nitrate CO₃²⁻ carbonate NH₄⁺ ammonium
•• ××
Covalent
Two non-metals share electron pairs for a full outer •• Cl × Cl ××
shell •
Multiple pairs shared → double/triple bonds •• ××
Dot-and-cross diagrams; a straight line = one bond
H
Dative (coordinate) lone pair
Both shared electrons come from one atom (a lone
pair ), drawn as an arrow H N H⁺
NH₃ + H⁺ → NH₄⁺ NH₄⁺
Once formed, it acts as a normal covalent bond H
Metallic + + + + +
Lattice of positive ions in a sea of delocalised + + + + +
electrons ; strong electrostatic attraction + + + + +
Higher ion charge (more electrons released) → sea of delocalised e⁻
+ + + + +
stronger
Bigger ions (e.g. Ba) → weaker (greater radius)
bonding ·
