Correct statements for an element with atomic | vedclass

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(B) The element with atomic number $9$ is Fluorine $(F)$,with electronic configuration $1s^2 2s^2 2p^5$.$(A)$ In $1s^2 2s^2 2p^5$,there are $9$ electr

Vedclass · Accepted Answer

$A$ and $C$ Only

Vedclass · Answer

(B) The element with atomic number $9$ is Fluorine $(F)$,with electronic configuration $1s^2 2s^2 2p^5$.$(A)$ In $1s^2 2s^2 2p^5$,there are $9$ electrons. Filling them: $1s$ $(2)$,$2s$ $(2)$,$2p$ $(5)$. Total up-spins $(m_s = +\frac{1}{2})$ are $1+1+3 = 5$ and down-spins $(m_s = -\frac{1}{2})$ are $1+1+2 = 4$. Statement $A$ is correct.$(B)$ The $2p^5$ configuration means $p_x^2 p_y^2 p_z^1$ or similar. The unpaired electron can be in any of the three $p$ orbitals,so $B$ is not necessarily true. Statement $B$ is incorrect.$(C)$ The last electron enters the $2p$ subshell where $n=2$ and $l=1$. Statement $C$ is correct.$(D)$ Angular nodes = $l$. For $1s$ $(l=0)$,$2s$ $(l=0)$,$2p$ $(l=1)$. Total angular nodes = $0+0+1+1+1 = 3$. Statement $D$ is incorrect.Therefore,only $A$ and $C$ are correct.

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