Ionization energy is the energy required to remove an electron from the outermost shell of an isolated gaseous atom. As metals can easily lose electrons therefore there ionization energy is less, in most cases they lose the electron on their own with release of energy or require very less energy to remove electron

One of the characteristic properties of non-metals is that they have low ionization energy. Let's understand this property in detail.

Ionization energy refers to the amount of energy required to remove an electron from an atom or ion in its gaseous state. It is typically measured in units of kilojoules per mole (kJ/mol). Non-metals have relatively low ionization energies compared to metals.

Explanation:
1. Definition of Ionization Energy:
- Ionization energy is the energy required to remove an electron from an atom or ion in its gaseous state.
- It is a measure of the attraction between the nucleus and the electron being removed.

2. Ionization Energy Trend in the Periodic Table:
- Ionization energy generally increases across a period (from left to right) in the periodic table.
- This is because the atomic radius decreases across a period, leading to stronger attraction between the nucleus and the outermost electron.
- As a result, it becomes more difficult to remove an electron, and the ionization energy increases.

3. Ionization Energy of Non-Metals:
- Non-metals are located on the right side of the periodic table.
- They have relatively high electronegativity, which means they have a strong attraction for electrons.
- This strong attraction makes it difficult to remove an electron from a non-metal atom, resulting in a low ionization energy.

4. Comparison with Metals:
- Metals, on the other hand, have low ionization energies.
- This is because metals have large atomic radii and a weak attraction for electrons.
- As a result, it is relatively easy to remove an electron from a metal atom, leading to a low ionization energy.

Conclusion:
Non-metals have low ionization energy because they have a strong attraction for electrons due to their high electronegativity. This makes it difficult to remove an electron from a non-metal atom. In contrast, metals have low ionization energies because they have large atomic radii and a weak attraction for electrons. Understanding the ionization energy of non-metals helps in explaining various chemical properties exhibited by these elements.