A neutral atom has the following electronic configuration: 1s 2 2s 2 2p 6 3s 2 3p 5
-How many electrons are in the M shell?
A)2
B)5
C)6
D)7
E)8

Question

A neutral atom has the following electronic configuration: 1s 2 2s 2 2p 6 3s 2 3p 5 
-How many electrons are in the M shell?
A)2
B)5
C)6
D)7
E)8

Quizplus · Accepted Answer

The M shell corresponds to the 3rd energy level (n=3), therefore it includes the 3s, 3p and 3d subshells. From the electronic configuration given, we can see that the 3s and 3p subshells are fully occupied with a total of 8 electrons (2 in 3s and 6 in 3p), while the 3d subshell is empty. Therefore, the number of electrons in the M shell is 8-0=8. The correct answer is D) 7.

A Neutral Atom Has the Following Electronic Configuration: 1s2 2s2

A Neutral Atom Has the Following Electronic Configuration: 1s² 2s²