Question

Ni has 4S as its outer subshell and not 3D. Why?

Answer 1

what do u think? can u guess?

Answer 2

I think I got your answer Chris. just go through this paragraph

When transition metals form ions, electrons are lost first from the 4s sub-shell rather than the 3d sub-shell. Thus Fe2+ ions have the electronic structure [Ar]3d6 rather than [Ar]4s23d4.

This occurs due to the presence of electrons in the 3d level, these repel the 4s electrons even further from the nucleus. Therefore, the 4s electrons are pushed to a higher energy level, higher than 3d. Consequently, when transition atoms become ions, the electrons from the 4s level before the 3d.

Answer 3

And therefore since 4s is at a much higher energy level (which now you know why) it is due to this reason that it's set as it's outer sub shell instead of 3d.

I hope this cleared it out for you :)

Answer 4

So, therefore, when transition metals become ions, they always lose the 4S subshell before the 3D one?

Answer 5

yup!