1. The electronic configuration of chlorine is 1. 2,7
II. 2,8,8,7
III. 2,8,7
IV. 2,7,8
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Chlorine has atomic number 17. Its electronic configuration is 2, 8, 7. It is the second-lightest of the halogens, it appears between fluorine and bromine in the periodic table.

III

Explanation:

From the periodic table, Chlorine(Cl) has 17 protons.

And when arranging the proton of elements each shell has a number protons it can take, i.e

2,8,8,8

The first shell can only take a maximum of 2 protons while the second shell upwards takes a maximum of 8 protons

Now we want to arrange Chlorine;

1st shell = 2

2nd shell = 8

2 + 8 = 10

17(no. of Chlorine protons) - 10

= 7

therefore,

3rd shell = 7

Therefore,

The electronic configuration of chlorine is

2,8,7

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.