Question

If I am asked to find the # of unpaired electrons in a molecule, do I just find the number of unpaired electrons for each atom and add them together?

For example, MgSO4.

Mg has 0 unpaired electrons. S has 2 unpaired electrons. O has 2 unpaired electrons.

Unpaired electrons = 2 + 4(2) = 10 unpaired electrons?

Answer 1

I think the best answer is no.

If you look at MgSO4 that is Mg^2+ + SO4^2-
You are correct that Mg as zero. It is 1s2 2s2 2p6 so all levels are filled and no unpairing. For SO4^2- you should draw the electron-dot structure. If you do that you will find zero unpaired electrons. This forum does not allow me to draw the structure of the sulfate ion but you can google it and get it. There are 32 electrons in the 2- ion and all are paired.

Answer 2

[AI-generated answer — Explain Bot]

To find the number of unpaired electrons in a molecule, you need to determine the electron configuration of each atom within the molecule. Unpaired electrons are usually found in the valence shell, which is the outermost shell of an atom.

In the case of MgSO4, let's determine the electron configuration for each atom:

- Magnesium (Mg): The atomic number of magnesium is 12, so the electron configuration is 1s² 2s² 2p⁶ 3s². Since it loses two electrons to form a stable divalent cation (Mg²⁺), it has a completely filled valence shell. Therefore, magnesium has 0 unpaired electrons.

- Sulfur (S): The atomic number of sulfur is 16, so the electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁴. Sulfur needs two electrons to complete its valence shell, so it can form two single covalent bonds. Thus, sulfur has 2 unpaired electrons.

- Oxygen (O): The atomic number of oxygen is 8, so the electron configuration is 1s² 2s² 2p⁴. Oxygen needs two electrons to complete its valence shell, so it can form two single covalent bonds. Therefore, oxygen has 2 unpaired electrons.

Now let's calculate the total number of unpaired electrons in MgSO4:

Mg: 0 unpaired electrons
S: 2 unpaired electrons
O: 2 unpaired electrons

Total unpaired electrons = 0 + 2 + 2 = 4 unpaired electrons.

So, the correct number of unpaired electrons in the MgSO4 molecule is 4, not 10.