Question

How the following properties varies in a group and in a period

(a) Atomic radius (b) Ionisation energy

(c) Electronegativity (d) Electron gain enthalpy​

Answer 1

Explanation:

${ \huge {\underline {\underline {\mathtt {\red{Atomic \: radius}}}}}}$

In a period, from left to right, with increase in the atomic number, the atomic radius decreases due to increase in the nuclear charge which increases the attraction of the nucleus for the valence electrons.

In a group, on moving from top to bottom, the ionic radius increases as a new energy level is added at each succeeding element but the number of valence electrons remains same.

${ \huge {\underline {\underline {\mathtt {\red{Ionisation \: energy }}}}}}$

Ionization enthalpy decrease down a group, but increase across a period.

${ \huge {\underline {\underline {\mathtt {\red{Electro \: negativity}}}}}}$

The higher the electronegativity of an atom, the greater its ability to attract shared electrons. The electronegativity of atoms increases as you move from left to right across a period in the periodic table. The electronegativity of atoms decreases as you move from top to bottom down a group in the periodic table

${ \huge {\underline {\underline {\mathtt {\red{Electron \: gain \: enthalpy}}}}}}$

Variation in electron gain enthalpy in the period: In the modern periodic table, on moving from left to right across a period, the atomic size of elements decreases and the effective nuclear charge increases. ... Variation of electron gain enthalpy in a group: Generally, when we move down in a group becomes less negative.

Answer 2

Answer:

Atomic radius, ionisation energy, Electronegativity, electron gain enthalpy varies along group and period in the periodic table.

Explanation:

Atomic radius : On moving from left to right in a period atomic radius decreases due to increase in the attraction of electrons by nucleus. From top to bottom in a group, the value of atomic radius increases due to increase in the number of shells.

Ionisation energy: In a period, ionisation energy increases from left to right and in a group,from top to bottom the value of ionisation energy decreases.

Electronegativity : It is the ability to attract electrons. In a period, this ability increases due to increased attraction by nucleus. But, in groups, electronegativity decreases from top to bottom.

Electron gain enthalpy: From left to right in a period, electron gain enthalpy increases,while in a group, the value of electron gain enthalpy decreases on going from top to bottom.