# Question #35427

Jun 26, 2017

The cation comes first/on the left and the anion is second/on the right in an ionic compound.
Cation = $C {a}^{2 +}$
Anion = $C {l}^{-}$

#### Explanation:

The cation comes first in an ionic compound. In this case, the cation is the first species (on the left), $C {a}^{2 +}$, and the anion is the second species (on the right), $C {l}^{-}$.

A cation has a positive charge, which is shown by the "+" superscript. E.g. $C {a}^{\textcolor{red}{2 +}}$

An anion has a negative charge, which is given by a "-" sign in the superscript. E.g. $C {l}^{\textcolor{red}{-}}$

The magnitude of the charges on each ion are important and are found by looking up a table of common ions. You need to memorise these common ions to know their charges. The overall charge on the ionic compound is neutral, so the charges have to add up to zero. This is why there are two $C {l}^{-}$ ions, to balance out the 2+ charge on the calcium cation. I.e. $\left(+ 2\right) + 2 \cdot \left(- 1\right) = 0$

Here is a great answer with more detail:

https://socratic.org/questions/how-do-you-write-an-ionic-formula-given-the-compound-name