Calcium Element Facts

Atoms of the element Calcium have 20 protons and 20 electrons in their neutral state. The number of neutrons in the nucleus varies. Calcium atoms are not found in their neutral state in nature, but rather form the stable Calcium cation Ca2+. It is this ion that we rely on for our health.

Calcium has a large number of possible isotopes ranging from 34-Calcium to 57-Calcium. These all have 20 protons in the nucleus and therefore range from having 14 Neutrons in 34-Calcium to 37 Neutrons in 57-Calcium. Six of these isotopes are either stable or have sufficiently long half lives to be considered stable. These are 40-, 42-, 43-, 44- and 46- and 48-Calcium. Of these the most abundant is 40-Calcium which makes up over 96% of the Calcium atoms in any given sample.

Electron Structure of Calcium

Calcium's 20 protons mean that the element has 20 electrons in its neutral state. These can be divided up into the first 4 electron shells using the Bohr method of 2, 8, 8, 2 which gives the correct number of two electrons in the outer shell. That Bohr model of Calcium is shown above, and results in the electron dot diagram shown to the left which shows only the outer shell electrons.

When we consider the electron details of subshell filling, we get a more accurate picture of the nature of electron distribution in this element. The subshell filling process gives the result 1s2 2s2 2p6 3s2 3p6 4s2 which is shown below.

Calcium atoms are very reactive and easily lose their two outer shell electrons to form the positively charged ion Ca2+. Because this is such a stable state for Calcium, it is never found as a metal in nature. The metal form of Calcium can be manufactured through the electrolysis of molten Calcium salts such as Calcium Chloride and Calcium Carbonate.

This metal is soft, reactive and silvery white in colour as are the rest of the Group 1 and 2 metals. It is sometimes used in the production of alloy metals.

The Calcium element forms a number of natural compounds with other elements and chemicals. All of these are salts, which means that the metal ion of Calcium is bonded through its positive charge to negatively charged ions. All these compounds have no overall charge; the charges of the Calcium and other parts balance each other out.

The most widely known example is Calcium Carbonate. This consists of the Calcium ion Ca2+ and the Carbonate ion, (CO3)2-. As can be easily seen, one Calcium ion and one Carbonate ion combine to give a neutral salt which is why the chemical formula for this salt is CaCO3.

Calcium Carbonate is an important mineral for bone strength. It is useful in this regard as it is almost insoluble in water, as are many Calcium salts.

In order to neutralize the 2+ charge of the Calcium element, two Chloride ions are needed as each has a -1 charge. This is why Calcium Chloride has the formula CaCl2.

The chemical formulae of other compounds of Calcium can also be worked out in this manner.