2.4 electrons, bonding and structure

electrostatic attraction between a positively charged metal ion and a negatively charged non-metal ion

• high melting and boiling points • do not conduct as solids • conduct when molten • soluble in water

strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

• low melting and boiling point • liquids/gases at RTP • do not conduct electricity

• large lattices • very strong covalent bonds • high melting and boiling points • do not conduct electricity

the bonding electrons in a bond are from one of the atoms

lattice of positive metal ions within a ‘sea’ of delocalised outer electrons

• high melting and boiling points • high heat and electrical conductvity • strong, malleable and ductile

2 BP 0 LP 180º

3 BP 0 LP 120º

4 BP 0 LP 109.5º

5 BP 0 LP 90º 120º

6 BP 0 LP 90º

3 BP 1 LP 107º

2 BP 2 LP 104.5º

3 BP 2 LP 120º

4 BP 2 LP 90º

ability of an atom to attract the bonding electron in a covalent bond

• the nuclear charge • distance between outer shells and the nucleus • level of shielding by other shells

across a period and up a group increases (F most)

induced dipoles < permanent dipoles < hydrogen bonding

dipole-dipole interaction between hydrogen and the lone pair of electrons on O/F/N

the weak intermolecular forces of attraction that arise between permanently polar molecules.

induced dipole-dipole forces are weak intermolecular forces of attraction present between all atoms and all molecules. the random movement of electrons introduces a instantaneous dipole which induces a neighbouring molecule