Question

Consider the following statements.

1. Ionization Energies decrease going left to right across a period.

2. Ionization Energies increase going up a group.

Which among the above statements is/are correct?

1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2

Answer 1

Correct Answer - Option 2 : 2 only

The correct answer is 2 only.

• Ionization Energy is the energy required to completely remove an electron from a gaseous atom or ion.
• The first ionization energy is the energy required to remove one valence electron.
• The second ionization energy is the energy required to remove a second valence electron.
• Ionization Energies increase going left to right across a period as the number of electrons increase and also due to the effective nuclear charge increases. (statement 1 is incorrect)
• It also increases going up a group because there are fewer electrons shielding the outer electrons from the pull of the nucleus. (statement 2 is correct)

• Ionization Energy is always positive.
• The highest ionization energies are noble gases because they have stable octet formation and require a high amount of energy to destroy that stable configuration.