Question

In p-elements of the 2nd period, 2p orbitals have higher energies than 2s ones due to

(A) stronger penetration to the core region and exposure to the full nuclear charge

(B) stronger penetration to the core region and exposure to the shielded nuclear charge

(C) weaker penetration to the core region and exposure to the full nuclear charge

(D) weaker penetration to the core region and exposure to the shielded nuclear charge

(E) additional compactness and nodeless structure of 2p orbitals

Answer 1

ANS-1.

** A 2s electron has more electron density near the nucleus than a 2p electron, it is penetrating the nucleus of the atom more than the 2p electron. The penetration power of an electron, in a multi-electron atom, is dependent on the values of both the shell and subshell.

*********Within the same shell value (n), the penetrating power of an electron follows this trend in subshells (m_l):

*********s>p>d>f

******And for different values of shell (n) and subshell (l), penetrating power of an electron follows this trend:

1s>2s>2p>3s>3p>4s>3d>4p>5s>4d>5p>6s>4f....

*******and the energy of an electron for each shell and subshell goes as follows...

1s<2s<2p<3s<3p<4s<3d<4p....

[Penetration is the ability of an electron to get close to the nucleus. The penetration of ns > np > nd > nf. Thus, the closer the electron is to the nucleus, the higher the penetration. Electrons with higher penetration will shield outer electrons from the nucleus more effectively. The s orbital is closer to the nucleus than the p orbital. Thus, electrons in the s orbital have a higher penetration than electrons in the p orbital. That is why the s orbital electrons shield the electrons from the p orbitals. Electrons with higher penetration are closer to the nucleus than electrons with lower penetration. Electrons with lower penetration are being shielded from the nucleus more.]

***(B) stronger penetration to the core region and exposure to the shielded nuclear charge

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