Question

Write the chemical formula of sodium oxide.

Answer 1

Hint: Chemical formula is an expression that is used to denote the number and types of elements that are present in one molecule of a compound. The chemical formula of sodium oxide contains two sodium atoms and one oxygen atom.

Complete step-by-step answer:
Sodium oxide is an ionic compound made up of sodium ions and oxide ions.
As we know that the electronic configuration of Na is $2,8,1$. Since only one electron is present in the outermost shell or valence shell. Hence, its valency is $+1$.
The electronic configuration of oxygen is $2,6$. Since six electrons are present in the outermost shell, so to calculate the valency for atoms 4 or more than four we have to subtract it from $8$. So, the valency of oxygen should be $(8-6)$ = $2$.

Element	Sodium	Oxygen
Valency	$+1$	$-2$

By using cross-over valencies, we get
The chemical formula of sodium oxide will be ${Na}_{2}O$.

Additional Information:
Sodium oxide is a white crystalline solid in appearance and it is a strong base in nature.
Sodium oxide is used in the manufacture of ceramic and glass products.
Sodium oxide when reacts with cold water then sodium hydroxide will be formed and it is an exothermic reaction.

Note: The possibility to make a mistake is that you may form $NaO$ instead of ${Na}_{2}O$. But $NaO$ cannot be formed as it is not a stable compound due to $-2$ charge on O-atom and $+1$ for Na-atom.