AS/A-level Chemistry: Covalent Bonding Structure

In AS/A-level Chemistry,

• Three- dimensional structure of atoms, bonded together by strong covalent bonds
• There are two types: Simple molecular structure and giant covalent structure

In AS/A-level Chemistry,

• Three-dimensional structure of molecules bonded together by weak intermolecular forces
• E.g. I₂, P₄, S₈, H₂O

Low melting and boiling points:

• Intermolecular forces have weak van der Waals’ forces
• Relatively small amount of energy is needed to break them

Conductivity:

• Are non-conductors of electricity because there are no charged particles free to move

Solubility:

• Simple molecular forces are soluble in non-polar solvents, such as hexane- because VDW forces form between simple molecular structure and non-polar solvent
• VDW forces weakens lattice structure

In AS/A-level Chemistry,

• E.g. Carbon (diamond), silicon and silicon dioxide- share similar bonding arrangement, whereas carbon (graphite)- different structure

High melting and boiling points:

• High temperatures is needed to break strong covalent bonds in lattice

Conductivity:

• Are non-conductors of electricity because there are no free charged particles to move, except in graphite

Solubility:

• Covalent bonds are insoluble in both polar and non-polar solvents
• Because bonds in lattice are too strong to be broken by either polar or non-polar solvents

• Each carbon atom makes 4 covalent bonds with 4 carbon atoms

• Structure:
  • Tetrahedral structure held together by strong covalent bonds throughout lattice
• Electrical conductivity:
  • Poor conductivity
  • NO delocalised electrons, as outer shell electrons are used for covalent bonds
• Hardness
  • Hard
  • Tetrahedral shape allows external forces to be spread throughout lattice

• Each carbon atom makes 3 covalent bonds with 3 carbon atoms

• Structure:
  • Strong hexagonal layer structure, but with weak van der Waals’ forces between layers
• Electrical conductivity:
  • Good conductivity
  • There’s delocalised electrons between layers
  • Electrons are free to move parallel to layers when a voltage is applied
• Hardness
  • Soft
  • Bonding within each layer is strong
  • Weak forces between layers allow layers to slide easily

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