Question

The electronic configuration of a transition elements in `+3` oxidatin stateis`[Ar]3d^(7)`. Find out atomic number.

Answer 1

`M^(3+) = [Ar]^(18) 3d^(7) `,i.e., it has 25 electrons.
It has been formed by loss of `3e^(-)` from metal M.
Hence, no. of electron in neutral metal atom `=25 + 3=28e^(-)`
`:. `No. of protons`=`Atomic no. `=28`