Here's why:
* Chemical symbols: In chemistry, we use symbols to represent elements. The symbol for sodium is Na and the symbol for chlorine is Cl.
* Formula: When elements combine to form a compound, we write their symbols together. In the case of sodium chloride, one sodium atom (Na) combines with one chlorine atom (Cl), giving us the formula NaCl.
So, while "NACL" might be a common misspelling, the correct and standard abbreviation is NaCl.