Question

Question #3b2a3

Answer 1

Ni is number `28` on the periodic table(Atomic number is `28`)

spdf `Ni :` `1s^2` `2s^2` `2p^6` `3s^2` `3p^6` `3d^8` `4s^2`

To check the total of all powers: `2+2+6+2+6+8+2 = 28`

The power of the subshell(s, p, d, f) gives the number of electrons on each subshell.

maximum values for subshells:
s `=2`
p `=6`
d `= 10`
f `=14`

Note : The reason why i didn't fill the `3d` with `10`, but rather put `2` in `4s` and 8 in the `3d` is that,

`4s` subshell is lower than the `3d` subshell and so it must be filled first.

So you fill it with `2` (maximum for an `s` subshell) before putting the rest in `3d`

Important fact :

The `4s` subshell is always filled before the the `3d` .