Why is the electron configuration for copper 1s22s22p63s23p63d104s1 instead of 1s22s22p63s23p63d94s2?

a filled sublevel is more stable than a half-filled sublevel.

the arrangement of electrons with the same spin is as small as possible.

the 4s orbital has higher energy than the 3d orbital.

electrons occupy orbitals of the highest energy levels first.

The reason why electron configuration for copper is written as 1s²2s²2p^(6)3s²3p^(6)3d^(10)4s¹ instead of 1s²2s²2p^(6)3s²3p^(6)3d^(9)4s² is because; Option A; A filled sublevel is more stable than a half-filled sublevel.

The reason for this is because when the sub shell is half full or completely full, the distribution of electrons are usually symmetrical.

Now, in this case of copper, we see that 3d^(10) 4s¹ was used instead of 3d^(9)4s².

We can see that 3d^(10) 4s¹ has a full d sub shell and a half full s-sub shell and as a result from the explanation above makes it more stable than 3d^(9)4s² that has a full s-subshell and a partially filled d-sub shell.

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A

Explanation:

There is a special stability conferred on an atomic configuration by filled and half half filled orbitals.

4s is half filled and is stable

3d is fully filled with 10 electrons and is stable.

This configuration is more desirable compared to the other one.