00:01
We're going to compare two states in the hydrogen atom in terms of both their energy and their angular momentum.
00:09
So a reminder that the energy can be calculated as minus 13 .6 electron volts over the principal quantum number n squared.
00:22
The angular momentum is calculated l is the square root of the angular momentum quantum quantum quantum.
00:32
L times l plus 1 times h bar.
00:36
H bar is a fundamental unit constant of angular momentum and is related to plank's constant through dividing by 2 pi.
00:54
But it is a fundamental constant.
00:59
But let's see.
01:00
So we have two states.
01:02
One is a 4f state.
01:04
And the other is a 5d state.
01:08
So the important thing to realize is that the first number given to you is the n quantum number.
01:16
The second letter is related to l for historical reasons.
01:23
We have angular momentum states labeled with s, p, d, and f, kind of a leftover from spectroscopy.
01:33
But s has l equals to zero, and it goes up from there.
01:46
It kind of makes it maybe a little bit easier to identify that that is an angular momentum number...