# Question #4ef6e

Nov 26, 2015

A calcium ion is written as ${\left[C a\right]}^{2 +}$.

#### Explanation:

Calcium atoms tend to lose 2 electrons from its valence shell to have a full shell of 8 electrons. For this reason, calcium's charge is ${2}^{+}$. To indicate the loss of 2 electrons, we write it as:

${\left[C a\right]}^{2 +}$

where:
[ ] = indicates that the atom is an ion
Ca = the element
2+ = the charge of calcium after losing 2 electrons

Note:
When an atom loses electrons, it has a positive charge.
When an atom gains electrons, it has a negative charge.