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

Jan 23, 2016

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 $\text{Ca}$ is on the second column/group, it originally had $2$ electrons. $2 - 2 = 0$, so $\setminus m a t h b f \left({\text{Ca}}^{2 +}\right)$ has no valence electrons .

Therefore, drawing the Lewis structure is actually not too hard; just write $\text{Ca}$, and mention somehow that it has a $2 +$ charge.

One way you could do it is to enclose $\text{Ca}$ in square brackets and put the $2 +$ up top like so:

${\left[\text{Ca}\right]}^{2 +}$