Question

An element Z has a valency of $3$ . What is the formula of the oxide of Z?

Answer 1

Chemical elements other than inert gases try to attain inert gas electronic configuration by gaining or losing electrons to get stability. The number of electrons lost or gained is termed as the valency of that element. Ion forms bonds with other elements or groups with opposite charges.

Complete answer:
Periodic table is the representation of chemical elements arranged in the increasing order of atomic numbers and arranged in the vertical columns and horizontal rows. The vertical columns are called groups and the horizontal rows are called periods. There are seven periods and eighteen groups in the periodic table.
The elements bel0ng to group $13$ are called boron family. The elements in the boron family are boron, aluminium, gallium, indium, tellurium and polonium. These all elements have three electrons in their outermost shell or orbitals. Thus, these all elements try to lose three electrons and try to get the nearest noble or inert gas configuration.
The valency of all these elements are $+ 3$ . So, these atoms become ions in the form of ${Z^{ + 3}}$ involving or forming bonds with the oxygen with the molecular formula of ${Z_2}{O_3}$ .

Note :
The compound will be ${Z_2}{O_3}$ . As the electrons lost by the two Z atoms are six, and the electrons gained by the three oxygen atoms are six. The electrons gained by one lion and the electrons lost by another ion in that compound must be the same.