Question

The formula of metal oxide of a metal A is ${A_2}{O_3}$. Determine the formula of its phosphate.
A) ${A_3}P{O_4}$
B) ${A_2}{(P{O_4})_2}$
C) $A{(PO)_2}$
D) $AP{O_4}$

Answer 1

The measurement of the net electric charge of a valence electron is called the electron valency, it also indicates the number of electrons necessary for an ion in order to attain a balanced electric charge. Also, the atoms having almost full or almost empty valence shells always tend to be more reactive.

Complete solution:
The valency of an atom is the number of electrons needed to be gained or lost in order to attain a noble gas electronic configuration. The valency of an element will always be a whole number and sometimes an element exhibits more than one valency.
In the given metal oxide ${A_2}{O_3}$
We know that ${o_2}$ has a valency of -2 and in order to attain a balanced state for the metal oxide $A$ must have a valency of +3.
Also, we know that phosphate ($P{O_4}$) has a valency of -3 and when the metal $A$ combine with the phosphate in order to form the corresponding metal phosphate it will be having a chemical formula $AP{O_4}$
$\therefore$Option D is the correct answer.

Additional information: The atom or molecule with zero valency shows the absence of net electric charge. The valency of an element or ion is determined by its outermost electrons and this measure shows the ability of an element to combine with other elements.

Note: Metals present in the first column of the periodic table have an electron valency of +1 and whereas the noble gas have an electron valency of 0 and are inert. Octet rule is the rule that ensures the outermost shell of a molecule or ion is having 8 electrons in the outermost shell.