Question

How can I write the formula for sodium chloride?

Answer 1

As the name suggests, the molecule of sodium chloride will contain the atoms of sodium and chlorine. In short, sodium chloride will form when the atoms of sodium interact with the chlorine atoms.

Complete step by step solution:
Let us study the formation of sodium chloride in detail;
Sodium- It is an alkali metal with atomic number of 11 resulting the ground state electronic configuration as $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{1}}$ . Thus, it needs to lose an electron to get stable.
Chlorine- It is a halogen with atomic number of 17 resulting the ground state electronic configuration as $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{5}}$ . Thus, it needs to get an electron to complete its octet.
When sodium and chlorine come together to form sodium chloride, sodium will lose one electron to chlorine. This would result in the formation of an ionic compound where sodium will have a positive charge on it and chlorine will have a negative charge.
Thus, this ionic reaction can be represented as;
$N{{a}^{+}}+C{{l}^{-}}\to NaCl$

Therefore, the formula of sodium chloride is NaCl.

Note: Do note that the equal charges will cancel each other and thus, the formula of sodium chloride is chargeless though the sodium is slightly positive and chlorine is slightly negative. Note when a cation and an anion with equal charge comes together to form a molecule, it will form a neutral molecule.