Question

What is the Lewis structure for `"Ca"^(2+)`?

Answer 1

The atomic number of calcium is `20`, and the atomic number of argon (a noble gas) is `18`, so calcium is on the second column of the periodic table.

Since we are talking about the `2+` cation, it already lost two electrons. We can tell because each electron brings a `1-` charge, and so losing a `1-` charge is like gaining a `1+` charge.

Also, since neutral `"Ca"` is on the second column/group, it originally had `2` electrons. `2-2 = 0`, so `\mathbf("Ca"^(2+))` has no valence electrons .

Therefore, drawing the Lewis structure is actually not too hard; just write `"Ca"`, and mention somehow that it has a `2+` charge.

One way you could do it is to enclose `"Ca"` in square brackets and put the `2+` up top like so:

`["Ca"]^(2+)`