# Is CaCl_2 an empirical formula? Why or why not?

Mar 5, 2017

A salt, like calcium chloride, consists of many ions, in this case $C {a}^{2 +}$ and $C {l}^{-}$. If the salt is in its solid state you can't say with calcium and which chloride ions belong together, because they are in a crystal grid, and every positive ion is surrounded by negative ions in a certain proportion and vice versa. And this proportion (in the case of $C a C {l}_{2}$) is 1:2.
For sodium chloride $N a C l$ it's a bit easier to visualize:
Every $N {a}^{+}$ ion has six $C {l}^{-}$ neighbours: above, below, left, right, in front and at its back. Same goes for every $C {l}^{-}$ ion. If you look through a $N a C l$ crystal you will see $N a - C l - N a - C l \ldots$ in all three perpendicular directions.