Question

1. In each of the following sets arrange the elements in increasing order of their negative electron gain enthalpy.

i) Carbon, nitrogen, oxygen.

ii) Oxygen, Nitrogen, Sulphur.

iii) Chlorine, sulphur, argon.

2. Suppose we have two elements 'X' and 'Y', the electron gain enthalpy of X and Y are -141 KJ and -748 KJ respectively. Out of X and Y which have the highest $\bf{negative}$ electron gain enthalpy.

$\large\underline{\textrm{Explanation Needed}}$​

Answer 1

Question 1 I) oxygen <nitrogen<carbon (as negative electron gain enthaply decreaces along a peroid )

2)sulphur<oxygen<nitrogen (as negative electron gain enthalpy decreases down a group)

3)argon<chlorine<sulphur(As negative electron gain enthalpy decrece along a peroid)

Question2 X have highest electron gain enthalpy because in negative value smaller magnitude is greater than the larger magnitude

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Answer 2

In chlorine and fluorine.

Cl has high electron gain enthalpy because the small size of F and there is very high electronic repulsion among the electrons of fluorine. This makes incoming of another electron not very favourable.

In sulphur and oxygen, sulphur has high electron gain enthalpy than oxygen because of larger size and lower electron density.

So, O < S < F < Cl

The Cl has a most negative electron gain enthalpy and O has a least negative electron gain enthalpy.

By considering the negative sign, the more negative value will be small and less negative value will be large.

Thus, the correct order will be Cl < F < S < O