Question About Valence Electrons

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Sameen Mahmood 3D
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Joined: Wed Jun 13, 2018 3:00 am

Question About Valence Electrons

Postby Sameen Mahmood 3D » Wed Oct 24, 2018 9:18 am

Are valence electrons the electrons in the outermost subshell or shell?

For instance, if looking at the valence electrons for phosphorous (Z=15), are we only considering the number of electrons in the 3p orbitals or all of the n=3 orbitals (3s and 3p)?

Prof. Lavelle said in class while he was drawing the orbitals for carbon that the outer valence are electrons are the two electrons in the 2p. Then why is it that when we draw the Lewis structure for Carbon, we draw it with four valence electrons?

Deepika Pugalenthi 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

Re: Question About Valence Electrons

Postby Deepika Pugalenthi 1A » Wed Oct 24, 2018 10:16 am

Valence electrons are the electrons located on the outermost shell, the shell being identified by the principal quantum number, n.

In the example you gave for phosphorus, you would consider the valence electrons for the whole energy level of n=3. Phosphorus would have 5 valence electrons. Its n=1 and n=2 shells are filled, leading to the remaining five electrons being in the n=3 shell.

During the lecture, Professor Lavelle must have just meant how many valence electrons are located in the 2p subshell. But, when drawing the Lewis structure, he included the 2s subshell electrons as well since they are also part of the n=2 shell.

I hope this helps!

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