Question:
Consider the last electron of an element having atomic number $9$ and choose the correct option.
Consider the last electron of an element having atomic number $9$ and choose the correct option.
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When determining the quantum numbers, consider the electron configuration and the shell the electron occupies.
Updated On: Jan 14, 2026
- Sum of total nodes = 1
- n = 2; l = 0
- Last electron enters in 2s subshell
There are 5e- with l = 0
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The Correct Option is B
Solution and Explanation
The element with atomic number 9 is Fluorine (F). The electron configuration of Fluorine is:
\[
1s^2 \, 2s^2 \, 2p^5
\]
The last electron (9th electron) enters the \( 2p \) orbital.
- For the last electron, the quantum numbers are:
- The principal quantum number (\( n \)) = 2 (since it is in the second shell).
- The azimuthal quantum number (\( l \)) = 0 (since it is in an \( s \)-orbital).
Thus, the correct answer is (2) \( n = 2; l = 0 \).
- For the last electron, the quantum numbers are:
- The principal quantum number (\( n \)) = 2 (since it is in the second shell).
- The azimuthal quantum number (\( l \)) = 0 (since it is in an \( s \)-orbital).
Thus, the correct answer is (2) \( n = 2; l = 0 \).
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