unpaired electrons [ENDORSED]

[Belle Calforda3f]

Can someone explain why for example: [kr]4d105s2 has no unpaired electrons?

[Lorie Seuylemezian-2K]

Determining whether or not electrons are paired can be done using an Aufbau diagram if every electron has a pair for example 2 arrows on every line than all electrons are paired! An easy trick is if the number of electrons in each sub shell is at the maximum then all electrons are paired.

[Chem_Mod]

The answer above is correct. Once you draw out the diagram, you'll see that the d-orbital electrons will not be paired, meaning there will be 5 unpaired electrons.

[Clarissa Molina 1D]

How can you tell if a an electron configuration represents the ground state or an excited state of an atom?