Answer: By losing its two outermost electron
Step-by-step explanation:
Calcium is a element that belongs to group 2 in the periodic table. It has an atomic number of 20, and an electronic configuration of 2, 8, 8, 2.
Hence, to form an octet structure, it gives off its two electrons as shown below:
Ca <----> Ca2+ + 2e-
Thus, by losing its two outermost electrons, a positively charged calcium ion (Ca2+) is formed