Explain the anomalous behaviour of chromium (z=24) and copper (z=29)
Answers
Answer:
z=696 is the correct answer
Using the Aufbau principle, you would write the following electron configurations
Cr = [Ar]
4
s
2
3
d
4
Cu = [Ar]
4
s
2
3
d
9
The actual electron configurations are:
Cr = [Ar]
4
s
1
3
d
5
Cu = [Ar]
4
s
1
3
d
10
To understand why this occurs, it is important to realize that...
1. Completely filled sublevels are more stable than partially filled sublevels.
2. A sublevel which is exactly half filled is more stable than a partially filled sublevel which is not half full.
3. Electrons are lazy and will do whatever places them in the lowest energy state = which is the most stable state
In both examples, an electron moves from the 4s sublevel to produce a 1/2 full 3d (Cr) or completely filled 3d (Cu). This gives the atom greater stability so the change is favorable.