Metallic bonding and structure L.O.:  Describe metallic bonding as the attraction of positive ions to delocalised electrons.  Describe giant metallic lattices.

The ‘sea of electrons’

Metallic bonding: o atoms are ionised o Positive ions occupy fixed positions in a lattice. o The outer-shell electrons are delocalised The metal is held together by the attraction between the positive ions and negative electrons.

Metals have high melting and boiling points. The have good electrical conductivity.

Structure of ionic compounds L.O.:  Describe structures with ionic bonding as giant ionic lattices.

Sodium chloride ionic lattice

All ionic compounds exist as a giant ionic lattice in the solid state

Why is the mp of MgO higher than the mp of NaCl? o The greater the charge, the stronger the electrostatic forces between the ions o and the greater the amount of energy required to break up the ionic lattice during melting

Ionic compounds are non-conductors of electricity when they are solids.

Ionic compounds are conductors of electricity when molten or dissolved in water.

Sodium and chloride ions surrounded by water molecules.

Describe the structures of simple molecular lattices. Describe the structures of giant covalent lattices. Explain physical properties of covalent compounds. Week 7 © Pearson Education Ltd 2008 This document may have been altered from the original

Crystal structure of solid iodine Week 7 © Pearson Education Ltd 2008 This document may have been altered from the original

Week 7 © Pearson Education Ltd 2008 This document may have been altered from the original Different forces in iodine

Week 7 © Pearson Education Ltd 2008 This document may have been altered from the original Tetrahedral structure

Week 7 © Pearson Education Ltd 2008 This document may have been altered from the original Hexagonal layer structure