Why copper and chromium show exceptional electronic configuration ?
Answers
Answered by
47
electron configurations
Cr = [Ar] 4s2 3d4
Cu = [Ar] 4s2 3d9
The actual electron configurations are:
Cr = [Ar] 4s1 3d5
Cu = [Ar] 4s1 3d10
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.
http://ericscerri.blogspot.com/2012/07/anomalous-configuration-of-chromium.html
It is important to note that this explanation is just looking at the examples of Cr and Cu. There are other elements which will have exceptions to the rules we have come up with to predict electron configurations. For example, W will follow the Aubau principle and not display behavior like that of Cr. This is due to the fact that the atoms and electrons know nothing of the rules we (humans) come up with to try to explain and predict their behavior.
Cr = [Ar] 4s2 3d4
Cu = [Ar] 4s2 3d9
The actual electron configurations are:
Cr = [Ar] 4s1 3d5
Cu = [Ar] 4s1 3d10
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.
http://ericscerri.blogspot.com/2012/07/anomalous-configuration-of-chromium.html
It is important to note that this explanation is just looking at the examples of Cr and Cu. There are other elements which will have exceptions to the rules we have come up with to predict electron configurations. For example, W will follow the Aubau principle and not display behavior like that of Cr. This is due to the fact that the atoms and electrons know nothing of the rules we (humans) come up with to try to explain and predict their behavior.
Answered by
17
Answer:
In Cr we can see that last d orbital is having 4 electrons in outermost shell to to attain stability it should have at least 5 electrons in its d subshell so it will take 1 electron from s subshell and now Cr will be more stable in its new electronic configuration. ... Hence, Cr and Cu are called exceptional configuration.
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