Question

1. use the aufbau diagram to draw the orbital notation of fe (3 points)

how many unpaired electrons does fe have? (2 points)

Explanation:

Step1: Determine the atomic number of Fe

The atomic number of iron (Fe) is 26, which means it has 26 electrons.

Step2: Fill electrons using the Aufbau principle

Fill electrons into orbitals in order of increasing energy. 1s can hold 2 electrons, 2s can hold 2 electrons, 2p can hold 6 electrons, 3s can hold 2 electrons, 3p can hold 6 electrons, 4s can hold 2 electrons, and then start filling 3d. After filling the previous orbitals, we have filled 2 + 2+6 + 2+6 + 2=20 electrons, and we need to fill 6 more electrons into 3d orbitals. According to Hund's rule, electrons first occupy empty orbitals singly with the same - spin before pairing up. So for 3d orbitals, we have 4 un - paired electrons.
The orbital notation:
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑↓
3p: ↑↓ ↑↓ ↑↓
4s: ↑↓
3d: ↑ ↑ ↑ ↑ ↓↓

Step3: Count the unpaired electrons

Count the number of single - occupied orbitals. There are 4 unpaired electrons in the 3d orbitals.

Answer:

The orbital notation is as described above, and Fe has 4 unpaired electrons.