What is the oxidation number of each hydrogen atom in a compound usually?
In order to assign an oxidation number to an atom bonded to another atom, you must assume that the more electronegative of the two atoms "takes" all the bonding electrons.
Hydrogen, as you know, has a single electron surrounding its nucleus, which consequently acts as its sole valence electron.
As a result, hydrogen can only form single bonds with other atoms because it can only share one electron. Therefore, any atom bonded to hydrogen that is more electronegative than hydrogen will "take" this valence electron for itself.
This will give hydrogen a
Keep in mind that when hydrogen is bonded to less electronegative atoms, such as in metal hydrides, it "takes" the bonding electron shared by the other atom for itself.
This gives it a
Take, for example, hydrogen in water,
This means that each of the two hydrogen atoms will have a
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In sodium hydride, on the other hand, hydrogen is more electronegative than sodium, so it will have a
The most common oxidation number of hydrogen will be