Question

Please explain how the valency of uranium (U) is 6 or 4.??
According to spdf rule-
7s2 5s3 6d1
So last atom is 1 it shall be 1
Please explain clearly how 6??

Answer 1

Electronic configuration of Uranium:1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 5f3 6d1 7s2

Or it can also be represented as : [Rn] 5f3 6d1 7s2

Valency= The maximum oxidation state shown by the element or in other words,no of electron in outermost shell.

#No of electrons in outermost orbit= 3+2+1=6
Hence its valency is given by 6.

# As we go down the group inert pair effect take place.
Inert pair effect: reduction of the oxidation states by two units as we go down the group, because the 2e in s block element refuse to take part in chemical reaction.

There it shows a valency of 4


NOTE:
1.valency is taken as the no of electron in its outermost “shell”/orbital.
2.valency is not the number outermost electron in “subshell”

Shell and subshell there is a difference..!!!!