d-block elements
These elements are also known as transition elements as their positioning and transition of properties lies between s and p block elements.
d-block elements have number of valence electrons equal to their group number, which is equal to the number of electrons in the "valence shell".
For example, Consider a transition metal or d block element Scandium. It's atomic number is 21.
Electronic configuration of Scandium(Sc)- [Ar] 3d¹ 4s², it has three electrons in its outermost shell and has a valency of three.
The electron configuration of scandium indicates that the ultimate shell(orbit) of scandium has a complete of electrons. But the electron configuration of scandium within side the Aufbau approach indicates that its ultimate electron([tex]3d^1\\[/tex]) has entered the d-orbital. Thus we can say that scandium has 3 valence electrons.
Therefore, we can say that d block elements have same number of outer electrons and valence electrons.
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