Question

What is an ionisation energy?

Answer 1

1. Ionization energy (IE) is defined as, the lowest possible energy required to expel the most loosely bound electron from an isolated gaseous atom of an element in its ground state.
2. The energy required to remove the electron from the second, third orbitals.. etc from an atom is called Successive ionization energy.
3. The second ionization energy of the atom is much higher than the first ionization energy because the cation formed due to the removal of the most loosely bound electron is very small than the parent atom.
4. They are represented as ${\mathrm{IE}}_2,{\mathrm{IE}}_3$ _, etc.
5. A large amount of energy is required to expel an electron from it.
6. Ionization energy depends on the following factors:

• Atomic size: The greater the atomic size, the electrons are farther away from the nucleus, which experiences a lesser force of attraction thereby having a lesser electronegativity.

• Nuclear charge: When the nuclear charge is greater, the force between electron and nucleus is also greater force thus increasing the electronegativity.
• Screening effect: It is defined as when an electron present between the nucleus and valence electron decreases the effect of the nucleus on the valence electrons.