Question

The element with highest ionisation potential from the elements of period 1, 2 and 3 is :

• A. Li
• B. He
• C. F
• D. Ne

Answer 1

Answer: (B)

He

The closer and more tightly bound an electron is to the nucleus, the more difficult it will be to remove, and the higher its ionization energy will be. The second ionization energy is the energy required to remove a second valence electron from the univalent ion to form the divalent ion, and so on. Successive ionization energies increase.

Group I elements have low ionization energies because the loss of an electron forms a stable octet. So, according to this, helium have highest ionisation potential among period 1, 2 and 3 elements. Helium has the highest ionization among all the noble gases.