What is an electron?Energy Of an Electron

What is an Electron?

The electron is the tiny particle of an atom. It is the outermost part of an atom contains electrons only. An electron is a negatively charged particle. The charge on the electron is but opposite to that on a proton. Also, the number if electrons us equal to the numbers of protons. The number of electrons or proton is called the atomic number.

                                  atomic number=no of electrons or no of protons in an atom

The electrons in an atom revolve around the core of an atom in a different orbit. The number and arrangement of electrons in any orbit defined by some rules:

The number of electrons in any orbit is given by 2n2 where n is the number of the orbit.

The first orbit contains                   2*1 = 2 electrons

The second orbit Contains             2*22  = 8 electrons

The third orbit contains                 2*32   = 18 electrons

Important Property of an electron:-

1)Charge on an electron, e   =1.602*10-19  Coulomb

2)Mass of an electron,m       =9.0*10-31  kg

3)Radius of an electron,r       =1.9*10-15 metre


The ratio of e/m of an electron is 1.77*1011 coulombs/kg. This means the mass of an electron is very small as compared to its charge. This property makes electron very mobile, which is greatly influenced by electric or magnetic fields.

Energy Of an electron:-

An electron has two types of energies one is kinetic energy and other is potential energy. Kinetic energy is due to its motion and potential energy due to the charge on the nucleus. The total energy of an electron is the sum of the kinetic and potential energy. The energy of an electron is increased as its distance from the nucleus increases.

The energy possesses by the second orbit electron is more than the first orbit electron. The electron in the third orbit has more energy than the second orbit electron. From this, you can say that electrons in the last orbit have more energy than the inner orbit electron so this last orbit electron play important role in a physical, chemical and electrical property of the material.