[Atarijedi]

Ok, so I am going to college for Pharmaceutical and Food Sciences and I haven't done chemistry in like 12 years. I am reading a free ebook on Chemistry called Introduction to Chemistry by Mark Bishop http://preparatorychemistry.com/Bishop_Atoms_First.htm. It's pretty decent in my opinion.

I'm in Chapter 5 and one of the subjects is covalent bonds, one of the examples is Water, and it shows the Hydrogen atoms bonding with the upaired electrons, which I understand, but the next example is a Hydroxide Ion, it says the Oxygen atom gains an electron. Where does that extra Electron come from? Maybe I missed something, or am forgetting something about the Oxygen atom?

Here is what it says

"In another common bonding pattern, oxygen atoms gain one electron and form one covalent bond with three lone pairs. The oxygen atom in the hydroxide ion has this bonding pattern." Section 5.4, Pg 193, Objective 17(g)

Then it shows a valence-bond model with electron-dot symbols.

[UG]

The electron comes from the cation that the hydroxide ion is in the solution with. For example, you have a piece of sodium metal and you put it into a beaker with water, the sodium forms Na⁺ so it loses an electron to the water molecule, so the oxygen now has nine electrons (well, sort of, maybe just for a sec ), so it 'kicks' out a hydrogen atom, and it has eight again, except now it is the hydroxide ion OH^-, this is where the electron came from. The reaction goes 2Na + 2H₂O  2NaOH + H₂. The two 'kicked' out hydrogen atoms combine to form hydrogen gas.