A metal (M) and a non - metal (X) form a compound with formula `M_(4)X_(3)` . Predict the electronic arrangements of M and X assuming that M has three occupied shells and X has two occupied shells. Also derive the formulae of (a) sulphate (b) dihydrogen phosphate ( c) hydroxide of ion of M.

Explanation

Formula `M_4X_3` corresponds to `M^(+3) X^(-4)`. M has three occupied shells K, L and M. The number of electrons in valence shell is equal to 3. The electronic arrangement could be 2, 8, 3 which corresponds to Z = 13, i.e., aluminium. X has two occupied shells K and L and the L shell must have 4 electrons. The electronic arrangement could be 2, 4 which corresponds to Z = 6, i.e., carbon.
(a) `Al^(+3) SO_4^(-2)`
(b) `Al^(+3) H2PO_4^(-)`
(c) `Al^(+3)OH^(-)`
Al_2(SO_4)_3" "Al(H_2PO_4)_3" "Al(OH)_3`