The element calcium has a total of four energy levels that each can hold a certain number of electrons. Its first and fourth energy levels hold two electrons each, and its second and third energy levels hold eight electrons each.
Calcium has an atomic number of 20, an atomic mass of 40 atomic mass units and an atomic symbol of Ca. In total, the element has 20 protons, 20 electrons and 20 neutrons. Its 20 electrons are held in each of its energy levels and orbit the nucleus of the calcium atom. The protons and neutrons are inside the nucleus.