1. To write a chemical equation, we need to know what are the reactants, which are the substances that reacts chemically in the equation. Without the reactants, we cannot deduce the products, which are the substances produced after the reaction.
2. First think about the chemical formula of table salt. It should be NaCl, as table salt is also known as sodium chloride, and Na and Cl ions have charges of +1 and -1 so their ratio is 1:1 which makes it NaCl.
Now, write the equation with the reactants on the left hand side and products on the right. Remember, since Chlorine is very reactive by itself, so, it naturally forms a diatomic molecule with formula Cl2.
Na + Cl2 → NaCl
Next, write the state of the substances. s for solid, l for liquid, g for gas, and aq for aqueous solutions.
Na (s) + Cl2 (g) → NaCl (s)
Last step, balance the equation. Make sure you have the same number of each atom on both sides of the equation. For example, if there's 2 Na atoms on the left hand side, make sure the right hand side has 2 too.
2Na (s) + Cl2 (g) → 2NaCl (s)