When do two reactants join with ionic bonding and when do they join with covalent bonding?
It depends of the atoms which make the bond: Nonmetallic compounds bond via covalent bonding, which means they share one or more electron pairs. If nonmetallic and metallic compounds bind with each other, the metallic compound releases its electron(s) and “donates” them to the nonmetallic compound. Thus the metallic compound becomes positively charged and the nonmetallic compound becomes negativiely charged, they are now ions which bond via an ionic bond (attrackted by their charges). The different kinds of compounds (wheter they are metallic, non metallic or semimetals) can be determined from the periodic system of the elements. An example for a metal atom would be Fe (Iron), whereas a nonmetallic compound would be C (carbon). Therefore two carbon atoms bond via covalent bonding and a Carbon atom would bond via an ionic bond with a Fe atom.
