In terms of electrons, how is a covalent bond different from an ionic bond? and ... Explain how attractions between molecules could cause water to have a higher boiling point than carbon dioxide?

Question

another question is why when scandium reacts with iodine, the formula of the ionic compound is ScI3?

Answer 1

With the electrons thing:
ionic=one atom gives electrons away to try to have a full outer energy level...after that, the atoms involved in the bond are ions (have + or - charges), and are attracted magnetically because one is positive, and one is negative. This is usually with nonmetal to metal elements.

Covalent=Atoms that share one or more electrons, and are linked because they physically share electrons. Usually this happens with a nonmetal and nonmetal, or metal and metal elements.

I'm not sure about the rest, but i think water might have a higher boiling point because its bonds are stronger?