Ionization Energy
Ionization energy can be defined as the amount of energy that can be used to remove an electron from the outermost energy level of an atom in a gaseous state. IE usually depends on the number of valent electrons possessed by an element. We have the first IE which is the amount of energy that is used in removing the first valent electron from the outermost energy level of an atom in a gaseous state. The IE of an atom of an element depends on the position in the periodic table where the element is located.
Group 2 Elements
Taking group 2 as an example and comparing the first 20 elements, beryllium is the topmost element followed by magnesium and then calcium. The ionization energy for all these elements differs whereby beryllium has got the least ionization energy of 900 KJ/mole followed by magnesium, calcium and lastly strontium with ionization energy of 550 KJ/mole. The ionization energy of elements in group 2 decreases down the group due to the successful increase in the number of energy levels down the group. As the number of energy levels increases, the forces of attraction holding the energy levels together becomes weak hence making the outermost electrons loosely attached. This reduces the amount of energy required by the atoms when ionizing.
Periodic Trend
Ionization energy increases across a period. Taking period three as an example, sodium has got smaller first ionization energy of 496 followed by magnesium with first ionization energy of 738 and then aluminum with much higher ionization energy. This is because of the increase in the nuclear forces of attraction as you move across the period. The electrostatic forces of attractions keep on increasing the period hence an increase in the amount of energy required when losing electrons.
Work cited
Sharpe, A. G., (2008). “Inorganic Chemistry” (3rd ed.). Prentice Hall. pp. 305–306. ISBN 978-0131755536.
