Chemistry - C2.4 (Ions and Ionic bonds), C2.5 (Simple molecules and covalent bonds), C2.6 (Giant covalent structures), C2.7 (Metallic Bonding)

positive ions

cations

negative ions

anions

Define ionic bonds

strong electrostatic attractions between oppositely charged ions (metals and non metals)

Properties of ionic compounds

High melting points and boiling points

Good electrical conductivity when molten or aqueous and poor when solid

generally soluble in water

Giant lattice structure

regular arrangement of alternating positive and negative ions

What are covalent bonds?

Formed when a pair of electrons is shared between two atoms (Non metal and non metal atoms)

properties of simple molecular compounds

low melting point and boiling point (weak intermolecular forces)

poor electrical conductivity

structure of graphite

• each carbon atom forms three covalent bonds with other carbon atoms.

• the carbon atoms form layers of hexagonal rings.

• there are no covalent bonds between the layers.

• there is one non-bonded - or delocalised. - electron from each atom.

structure of diamond

each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral, three-dimensional structure

properties of diamond

high melting and boiling points.

Diamond's many covalent bonds are strong, and substantial energy is needed to break them.

metallic bonding

electrostatic attraction between the positive ions in a giant ‘sea’ of delocalised electrons

properties of metals

malleable

good conductor of electricity and heat

shiny

solids at room temperature (except for mercury)