As we know, water is a covalently bonded molecule. However, the hydroxides - such as sodium hydroxide - are ionic compounds. Both of these are similar, although the difference between both is a sodium atom instead of a hydrogen atom.
Now, both hydrogen and sodium have one outer electron, which makes me come onto my question:
Could sodium share its outer electron with the OH group, like hydrogen does in water molecules, to form a normal covalent bond? Or, could hydrogen lose its outer electron to form a cation, and ionically bond to OH-, like what happens in sodium hydroxide?
Long story short: why is water covalent, whilst the hydroxides are ionic, if the difference is just another atom instead of hydrogen?