The balanced equation for the reaction between sodium (Na) and chlorine (Cl2) to form sodium chloride (NaCl) is 2Na + Cl2 -> 2NaCl. This equation is balanced because it has an equal number of each type of atom on both sides of the reaction arrow.
The equation is balanced because the number of each type of atom is the same on both sides of the equation. There are two Cl atoms on the left side and two Cl atoms on the right side, two Na atoms on the left side and two Na atoms on the right side, and two I atoms on the left side and two I atoms on the right side.