1.5 - Structure

Question 1

Describe the structure of ionic compounds, for example sodium chloride

Answer 1

• Giant ionic lattice.
• Contains an ordered array of tightly packed ions.
• The lattice consists of sodium ions (Na+) surrounded by chlorine ions (Cl-).
• The ionic bonds result from strong electrostatic attraction between neighbouring ions in the lattices.
• The ions are prevented from moving by the lack of space and strong electrostatic attractive forces.
• As a result no charged particles can move within the lattice so it does not conduct electricity in its solid state.
• The inability of the ions to move past each other in the lattice also explains why many ionic solids are hard materials.

Question 2

Describe the structure of metals

Answer 2

• Metallic bonding forms metallic lattices.
• The electrons in the outer shells of metal atoms become detached from the atom and move freely through the metal.
• As a result, metals contain an array of positively charged metal ions in a ‘sea’ of delocalised electrons.
• The metal ions are bonded together by forces of attraction between the metal ions and the delocalised electrons; a type of bonding referred to as metallic bonding.
• Metallic bonds are similar to covalent bonds (both types of bonding involve the sharing of electrons and can create strong bonds).
• The metal ions are tightly packed due to these strong metal bonds, producing a hard, dense solid