Explain order of ionisation enthalpy of alkali metal when we go top to

1.	Explain order of ionisation enthalpy of alkali metal when we go top to bottom.
Answer» Solution : Ionisation enthalpy and atomic radius are corelated with each other. When we go TOP to bottom in group ionisation enthalpy decreases and atomic radius increases. In same group when we go top to bottom outer most electron is arranged more distance with NUCLEUS so SHIELDING effect becomes more. In this situation, when we go top to bottom in same group shielding effect is more important than effective nuclear charge so LESS energy required to lose electron. So due to shielding effect ionisation enthalpy is decreases.

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