Bonding in methane The simplest alkane, methane, has the molecular formula CH 4. Justify that formula. Write the electronic configuration of carbon and show how this supports your argument. Experiments have shown that all four bonds in methane are identical. Show how this is possible. H HH H C

The bonding between C and H is covalent This involves the sharing of a pair of electrons between two atomic nuclei (each atom involved contributes an electron to the pair)

Ground state configuration of carbon 2p z 2p y 2p x 1s energy 2s

Excited state configuration of carbon 2p z 2p y 2p x 1s energy 2s

energy 1s “Hybridised configuration” of carbon 3 x sp 3 hybrid atomic orbitals (all with the same shape and energy)

Atomic orbitals The shapes of s and p atomic orbitals x z y p z orbital y x z x z y x z y s orbital p x orbital p y orbital

Overlap of two s orbitals to form a covalent bond

Overlap of s and p x orbital

Overlap of s and p y orbital

Overlap of s and p z orbital