# Can two atoms with the same amount of electrons but differing electronic configurations be considered isoelectronic?

Can two atoms with the same amount of electrons but differing electronic configurations be considered isoelectronic?

For example, would we consider yttrium(I) $$(\ce{Y+})$$ with configuration: $$\ce{[Kr] 5s^1 4d^1}$$ and strontium $$(\ce{Sr^0})$$ with the configuration $$\ce{[Kr] 5s^2}$$ to be isoelectronic?

$$(\ce{Y+})$$ with configuration: $$\ce{[Kr] 5s^1 4d^1}$$ and strontium $$(\ce{Sr^0})$$ with the configuration $$\ce{[Kr] 5s^2}$$ are not isoelectronic. In order to be isoelectronic the two atoms would have to have the same electronic structure as well as the same number of valence electrons.