00:02
Hi there.
00:03
Welcome to question number 86.
00:07
86 actually is three questions in one.
00:09
We have a part a, a part b, and a part c.
00:12
So let's get started with part a.
00:15
Part a asks about the third energy level.
00:19
So that means the principal quantum number is n equals three.
00:22
And it wants to know how many sub -levels there are.
00:25
Well, when n equals three, remember, l ranges from zero to n -minus one.
00:32
So l.
00:32
L could be 0, 1, or 2.
00:37
This gives us 3 sub -levels.
00:45
So when n equals 3, there are 3 sub -levels.
00:51
Moving on to question b.
00:54
Question b wants to know about these sub -levels, and if any of them contain a set of equivalent orbitals.
01:02
So let's think about what the letters for l mean, or the numbers rather for l.
01:08
When the angular momentum quantum number or l is zero, that represents s orbitals, when l equals 1, that represents p, and when l equals 2, that represents d.
01:23
So s orbitals, there's only one of those.
01:26
Each time you have an s, there's only one of those...