Question

define the ionisation enthalpy and explain its change in group and periods
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Answer 1

Answer:

Explanation:

Ionization enthalpy of an element can be defined as the amount of energy required to remove an electron from an isolated gaseous atom in its gaseous state. Ionization enthalpy depends on the following factors:

Penetration effect

Shielding effect

Electronic configuration

Across a period

While moving left to right in a period, the atomic radius decreases. So if the size of an atom decreases, the attractive force between the nucleus and the outermost electrons increases due to which across a period in the periodic table ionization energy generally increases.

In a group

While moving down in a group ionization energy of elements decreases as the number of shells increases down the group. The outermost electrons will be far away from the nucleus, and the effective nuclear charge will be less. Secondly, the shielding effect also increases down the group as the number of shells increase which in turn results in decreasing ionization energy.