Question

Predict the formulae of the stable binary compounds that would be formed by the combination of the following pairs of elements.
(a) Lithium and oxygen

(b) Magnesium and nitrogen
(c) Aluminium and iodine

(d) Silicon and oxygen
(e) Phosphorus and fluorine

(f) Element 71 and fluorine

Answer 1

(i) Alkali metal lithium (with 1 valence electron) combine with group 16 element oxygen (having valence of 2) to form $L{i}_{2}O$.
(ii) Alkaline earth metal magnesium (with 2 valence electrons) combines with group 5 element nitrogen (having valence 3) to form $M{g}_3{N}_2$.
(iii) Group 13 element aluminum (with 3 valence electrons) combines with group 17 element iodine (a halogen with valence 1) to form $Al{I}_3$.
(iv) Group 14 element silicon (with a valence of 4) combines with group 16 element oxygen ( having valence 2) to form $Si{O}_2$.
(v) Group 15 element phosphorous (with valence 3 or 5) combines with group 17 element fluorine (a halogen with valence 1) to form $P{F}_3$ or $P{F}_5$.
(vi) Element 71 with 3 electrons in the valence shell $\left(4f^{14}5d^{1}6s^2\right)$ combines with group 17 element fluorine (a halogen with valence 1) to form $E{F}_3$ where E is the symbol of the element.