When oxygen combines with hydrogen, how many valence electrons does oxygen end up with?
Oxygen starts with six valance electrons and ends with six valance electrons but after bonding has parts of the densities of 8 electrons
Chemical bonding does not increase the valance electrons. Oxygen has 6 valence electrons. Bonding is sharing of valance electrons
The electron density of two of the valance electrons of Oxygen are shared with the Hydrogen atoms. The Hydrogen atoms is turn share part of the electron density of their single electron with Oxygen.
This means that there are parts of 8 electron densities around the Oxygen. This does not increase the number of valance electrons of Oxygen. (Note the sharing is very unfair, Oxygen gets more than its
share of the electron densities of the two electrons used for the chemical bond.