First and Second Ionisation Energies

“The ionization potential, ionization energy or E

I

of an atom or molecule is the energy required to remove one mole of electrons from one mole of isolated gaseous atoms or ions. More generally, the nth ionization energy is the energy required to strip it of an nth mole of electrons after the first n − 1 mole of electrons have already been removed. It is considered in physical chemistry as a measure of the "reluctance" of an atom or ion to surrender an electron, or the "strength" by which the electron is bound; the greater the ionization energy, the more difficult it is to remove an electron. The ionization potential is an indicator of the reactivit y of an element. Elements with a low ionization energy tend to be reducing agents and to form salts.

Values and trends

The next ionization energy involves removing an electron from an orbital closer to the nucleus. Electrons in the closer orbital experience greater forces of electrostatic attraction, and thus, require more energy to be removed. In order to determine how many electrons are in the outermost shell of an element, one can use the ionization energy. If, for example, it required 1,500 kJ/mol to remove one mole of electrons and required 6,000 kJ/mol to remove another mole of electrons and then 5,000 kJ/mol, etc. this means that the element had one electron in its outermost shell. This means that the element is a metal and in order for this element to achieve a stable complete outer shell, it looks to destroy one electron. Thus, the first electron is easy to remove and consequently the ionization energy is low. Notice, however, that once the stable complete outer shell has been formed, it becomes much more difficult to remove the next electron. If that electron can be removed the consequent one can be removed a bit more easily.

Atomic Radius