Question

what atoms usually form coordinate covalent bonds

i couldn't find this anywhere

also

i just want to make sure
is the electronegativity difference range for polar covalent bonds .4 - 2.1 paulings?

Answer 1

yes on the electronegativeity

coordinate covalent bonds?Often these contain oxygen, sulfur, nitrogen, and halide ions. The most common ligand is water(containing oxygen), then ammonia (NH3), then anions fluorides, chlorides.