Question

What is the significance of the terms ‘isolated gaseous atom’ and ‘ground state’ while defining the ionisation enthalpy and electron gain enthalpy?

Answer 1

Basically, a gaseous atom is an atom in its gaseous state i.e. it has been excited from its original state and has been crossing all the forces of attraction to be free in the gaseous state. Whereas, ground state describes the state of an element when no external energy is provided to it.

Complete answer:
Let us discuss the above given terms firstly;
Isolated gaseous atom-
When an atom is free from other atoms in nature in the gaseous state, it is called as the isolated gaseous atom. For further separation of this atom, no energy is required.
Ground state-
The lowest possible state of an atom is the ground state. When no energy is applied on the stable atom, it remains in its ground state.
Ionisation enthalpy-
The amount of energy required to remove an electron from an isolated gaseous atom in its gaseous state is known as ionisation enthalpy.
Electron gain enthalpy-
The amount of energy released when an electron is added to an isolated gaseous atom is known as electron gain enthalpy. During this process i.e. addition of electron; energy can either be released or absorbed.

Note:
Do note that there is a difference between the two given terms i.e. isolated gaseous atom and ground state but has equal importance while we determine electron gain enthalpy and ionisation enthalpy of the atom.