ES - CI3.1 Chemical Bonding

Formation of Ions

• Groups 1 and 2 metal elements can lose electrons to make cations
• Non-metal elements (have more than 3 electrons) to form anions

Ionic Bonding

• Metals + Non-metals = ions are formed
• Electrons are transferred from the metal to the non-metal
• Cations and anions formed are held together by electrostatic bond
• Use electron dot-cross diagrams to represent:

• Opposite charged ions attract = ionic bonding
• Properties: high m.p, dissolve in water and conduct electricity when molten

Covalent Bonding

• Contain only non-metal elements
• Electrons are shared between atoms
• Shared electrons count as part of the outer shell of both atoms
• Held together by the +ve nucleus attracting the -ve electrons
• Electrons that form bonds = bonding pairs
• Electrons not involved = lone pairs

eg. dot and cross diagram…