Covalent

• In covalent bonding atoms share electrons
• Simple covalent are made up of individual molecules
• giant covalent are made of a network of covalently bonded atoms - also known as a macromolecular structure
• in graphite, carbon atoms are arranged in layers of flat hexagons with weak van der waals forces between layers
• in graphite, each carbon is bonded to three other carbons and the fourth outer electron is delocalised so an electric current can flow
• graphite has a high melting point
• graphie has a low density
• in diamond each carbon is bonded to 4 other carbons
• Diamond has a very high melting point and is extremely hard
• in a dative/co-ordinate covalent bond one of the atoms provides both of the shared electrons
• a dative covalent bond forms when one of the atoms has a lone pair of electrons and one has none available to share
• the ammonium ion (NH4+) is formed by co-ordinate bonding when the nitrogen atom in ammonia donates a pair of electrons to a proton (H+)
• Simple covalent compounds have strong covalent bonds between molecules but weak intermolecular forces
• some simple covalent molecules dissolve in water depending on how polarised the bond is