Question

What is Ionisation energy​

Answer 1

In physics and chemistry, ionization energy or ionisation energy, denoted Eᵢ, is the minimum amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated neutral gaseous atom or molecule.

Answer 2

In physics and chemistry, ionization energy (American English spelling) or ionisation energy (British English spelling), denoted Ei, is the minimum amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated neutral gaseous atom or molecule. It is quantitatively expressed as

X + energy → X+ + e−

where X is any atom or molecule capable of ionization, X+ is that atom or molecule with an electron removed, and e− is the removed electron. This is generally an endothermic process. Generally, the closer the outermost electrons are to the nucleus of the atom , the higher the atom's or element's ionization energy.