Question

What period 3 element has the following ionization energies (all in kj/mol)? IE_1 = 1012 IE_4 = 4960 IE_2 = 1900 IE_5 = 6270 IE_3 = 2910 IE_6 = 22, 200 Si S P Cl Mg

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Answer 1

the answer is P (phosphorus)

reason:

If you look at the data, the difference between IE 5 and IE 6 is huge compared to other. This means electron removal after 5 electrons (IE 5) is becomes difficult and most probably this is due to the next electron is occupied in lower orbital. (change in the principle quantam number - n)

from the above list

a) Si Electron configuration: 1s2 2s2 2p6 3s2 3p2; (n) happens after IE4

b) S Electron configuration: 1s2 2s2 2p6 3s2 3p4; (n) happens after IE6

c) P Electron configuration: 1s²2s²2p⁶3s²3p³ ; (n) happens after IE5

d) Cl Electron configuration: 1s2 2s2 2p6 3s2 3p5 ; (n) happens after IE7

e) Mg Electron configuration: 1s2 2s2 2p6 3s2 ; (n) happens after IE2