Question

how come the electron configuration for ground-state copper atom is [Ar]4s1 3d10 instead of [Ar]4s2 3d9?

Answer 1

copper is most commonly used as example of this kind of exceptions where energy levels of s and d orbitals are similar and regarding energy it is more favorable that one electron from s orbital fills d orbital and complete it than s orbital to be full, that coul be explained like this: by moving one electron from lower s shell to upper d shell electron - electron repulsion is more reduced and thus greater stability and lower energy is gained

Answer 2

hmm if i remember right cobalt and copper are exceptions right?

Answer 3

i know there is also chromium but as you go down in periodic table you can find more exceptions...

Answer 4

oh chromium..i remember it was c lol