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### Help on 2.51

Posted: **Thu May 10, 2018 10:13 pm**

by **Amanda Cardenas 1J**

I need help on part a and d of 2.51. Any help is useful.

2.51: How many unpaired electrons are predicted for the ground-state configuration of each of the following atoms:

(a) Bi

(d) Ni

### Re: Help on 2.51

Posted: **Thu May 10, 2018 10:23 pm**

by **NatalieSDis1A**

a. The electron configuration for Bi is [Xe] 4f^14 5d^10 6s^2 6p^3. All of the shell are full except for the p block so we want to look at that. I think it's helpful to draw out the orbitals for this. if you look at the 6p orbital ___ ___ ___ we would draw three parallel arrows (according to Hund's rule) and have 3 unpaired electrons.

d. Ni: [Ar] 3d^8 4s^2. For this one we want to look at the 3d shell because it is not completely full.

___ ___ ___ ___ ___

For the first five electrons in d we would fill each orbit with parallel electrons. The remaining 3 would form pairs in the first 3 orbital. This leaves 2 unpaired electrons.

### Re: Help on 2.51

Posted: **Thu May 10, 2018 11:06 pm**

by **Bijal Luhar**

Hello,

a. the first step in solving these problem is writing out the full electron configuration;

Bi: [Xe] 6s2 5d10 6p3

-From here we see that the S orbital is completely filled with its 2 electrons, we see that the D orbital is completely filled with its own 10 electrons, however we notice that the P orbital is not completely filled with the 6 electrons, it only has 3. Therefore, there are 3 electrons are essentially "missing" and are the ones that are not paired

b. we would repeat the same process for B. Just remember that S should have 2 electrons, D should have 10, and P should have 6. If these numbers do not appear simply subtract the value given from the value necessary for a full shell. This will give you the amount of unpaired electrons

### Re: Help on 2.51

Posted: **Fri May 11, 2018 7:47 pm**

by **Alejandro Salazar 1D**

To find the unpaired electrons, select the outer most valence electron, identify if it is s d p f orbital, draw out how many electrons on the outer most valence electron, and determine how many are unpaired.

I attached a file to illustrate