Question

Arrange these following atoms in order of decreasing first Ionization Energy

[Ne]3s2 3p5
, [Ar]4s2 3d10 4p3
, [Ar] 4s2 3d10 4​

Answer 1

Ionisation energy

Explanation:

• Generally, it is the minimum amount of energy that one must need to remove the electron which is most loosely bound in an isolated neutral gaseous atom or molecule.
• Using the above definition, we can arrange the given atoms into their decreasing first ionization energy.

1. [Ne]3s2 3p5
2. [Ar]4s2 3d10 4p3
3. [Ar*] 4s2 3d10 4p2​

[Ne] will have maximum ionisation energy due to half-filled orbital, and [Ar] will have more ionisation energy due to more exchange numbers in p orbitals that correspond to more exchange energy.

Thus, the order will be

[Ne] ≥ [Ar] ≥ [Ar*]