i know it in reference to ozone, where it's a covalent bond, but the electrons aren't actually shared equally. ie one atom provides more electrons than the other
yep the pair of electrons that are shared come from the one atom. with NH4+ the 4th H does not share its electron, both electrons come from the N.
<div pre>
H
:<-----coordinate covalent bond
H: N :H
..
H
</div>
sorry bout d bad diagram, but the top H is the parasite usin the coordinate covalent bond.