The Role of Electrons

Electron Shells

Electrons revolve around the nucleus in shells or energy levels. These shells are numbered 1,2,3,4 and are also lettered K,L,M,N. In an atom, the number of electrons each shell can contain are: 1(K): 2 electrons, 2(L): 8 electrons, 3(M): 18 electrons, 4(N): 32 electrons.


All atoms are electrically neutral as the number of protons are equall to the number of electrons. Being equal, this balances the positive and negative charges. The atom becomes charged if the balance is changed. A charged atom is also known as an ion. There are two types of ions, positive ions and negative ions. An ion becomes positive when it loses an electron and becomes negative when it gains one.