00:02
There, this question wants us to write the complete ground -state electron configuration for technetium.
00:10
Technetium has the symbol t -c, and looking at the periodic table, we see that its atomic number is 43.
00:16
Well, that atomic number is important because that tells us the number of protons.
00:21
But more importantly, for writing electron configurations, we know that if it has 43 positive charges, it must also have 43 negative charges to be a neutral atom.
00:33
All right, so we are trying to write an electron configuration for 43 electrons.
00:39
We're going to follow the alfow principle, where we fill in the electrons, starting with the lowest energy level, and build up until we get to 43.
00:48
So we'll start off with 1s, and we'll put two electrons in that.
00:52
After the 1s comes the 2s.
00:55
That also holds two electrons, followed by the 2p, being p orbitals, it holds 6.
01:01
So so far we have 2, 4, 10, electrons.
01:04
In their orbitals.
01:06
Let's go on to the third period.
01:08
We fill in the 3s with 2.
01:10
We fill in the 3p with 6, but then according to alphbow, the 4s has lower energy than 3d...