Question

How many unpaired electrons are there in tungsten?

Answer 1

There are four unpaired electrons in the `"5d"` sublevel (subshell).

Explanation:

The electron configuration of tungsten, `""_74"W"` is:

`"1s"^2"2s"^2"2p"^6"3s"^2"3p"^6"3d"^10"4s"^2"4p"^6"4d"^10"4f"^14"5s"^2"5p"^6"5d"^4"6s"^2"`

or

`["Xe"]"4f"^14"5d"^4"6s"^2"`

There are five orbitals in any d sublevel. A single, unpaired electron must enter each of the five orbitals before electrons can be paired. The sixth electron would form a pair in one orbital. However, `"W"` has four `"5d"` electrons, so they are all unpaired.