Question

What is the quantum number of last electron in chlorine?

Answer 1

See below.

Explanation:

The electron configuration of `"Cl"` is `color(red)(1"s"^2)color(green)( 2"s"^2 2"p"^6)color(blue)( 3"s"^2 3"p"^5`.

• The last electron is in `"M"` orbit.
• It is in `"P"` orbital.
• `"P"` orbital has three sub-shell. The last `"e"^-` stays in `"P"_y` orbital.

So, the quantum number will be

`color(red)(ul(bar(|color(red)(n=3)" ; "color(green)(l=1)" ; "color(blue)(m_l=0)" ; "color(brown)(m_s=-1/2)|`

The electron in such a manner fills the orbital of an orbit with same spin then it takes the different spin.

So, last electron is in `"P"_y` orbital.

Hope it helps..
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