Question

When placed in the order of increasing ionization energy, what is the correct order for $O,{O^{ + 1}},{O^{ - 1}}$ ?
A. $O > {O^{ + 1}} > {O^{ - 1}}$
B. ${O^{ - 1}} > {O^{ + 1}} > O$
C. ${O^{ + 1}} > O > {O^{ - 1}}$
D. ${O^{ - 1}} > O > {O^{ + 1}}$

Answer 1

Hint: Ionization is the process of removing an electron from an orbit and transferring it to the outside of the atom. Ionization energy is equal to the difference in energy between the energy of the electron in the initial orbit and the energy of the electron outside the atom, because each orbit has a characteristic energy.

Complete answer:
Factors that determine the ionization energy are as follows:
It is usually more difficult to remove one electron when the ionization energy is high. The attraction forces are also governed by a number of elements.
The electrons are strongly attracted to the nucleus if it is positively charged.
When an electron is close to or near the nucleus, the attraction is stronger than when the electron is further away.
The attraction forces between the outer level and the nucleus are reduced when there are more electrons between them.
When there are two electrons in the same orbital, they experience some form of repulsion. This creates disturbances in the attraction of the nucleus. Hence, ionization energy will be less in paired electrons as they can be removed easily.
Therefore, we can conclude that it is easier to remove an electron from a neutral atom than a positive ion and is even more easy to remove it from a negative ion.

So, the correct answer is “Option C”.

Note:
An electron's ionisation energy increases with the atomic number of the atom and decreases with higher energy orbitals. As we proceed from left to right across the periodic table, the ionisation energy increases due to the decreasing atomic radius.