Problem: How many unpaired electrons would you expect on chromium in ammonium chromate?

FREE Expert Solution

Step 1: Recall that for a neutral element, Atomic number = # of protons = # of electrons

The atomic number of Cr is 24 which means Cr has 24 electrons.


The location of Cr in the periodic table is shown below:



Based on the figure, Cr belongs in the d-block in Period 4 so its electron configuration will contain the 4s and 3d subshells

Recall that: 

s–subshell can hold a maximum of 2 electrons

p–subshell can hold a maximum of 6 electrons

d–subshell can hold a maximum of 10 electrons

f–subshell can hold a maximum of 14 electrons


Starting from 1s, the electron configuration for Cr is:


Cr: 1s22s22p63s23p64s23d4



Step 2: In ammonium chromate, the charge of Cr is +6.

The +6 charge means 6 e were lost. Therefore, we need to subtract 3 e starting from the highest energy level (4s).


The electron configuration for Cr6+ is:


Cr6+: 1s22s22p63s23p6


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Problem Details

How many unpaired electrons would you expect on chromium in ammonium chromate?

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Our tutors have indicated that to solve this problem you will need to apply the Orbital Diagrams concept. If you need more Orbital Diagrams practice, you can also practice Orbital Diagrams practice problems.