Concept:Ionic Bonds:Low positive charge and large size of cation and a small charge on anion and small size of anion favor the formation of ionic compounds.Ionic bond formation occurs via electrostatic attraction between two ions.One ion is positively charged and the other is negatively charged like in NaCl.?Covalent bonds:High positive charge and small size of cation and a high charge on anion and large size of anion favor the formation of covalent compounds.Covalent bond formation occurs when there is electron sharing occurs between two atoms.The electron pair is shared equally between the atoms forming the bond-like in Cl2.Co-ordinate bond:It is formed by the complete donation of electrons from one atom to the other.The atom which donates the electron pair is called the donor atom.The atom accepting the electrons is called the acceptor.?Explanation:SO2 is a covalent molecule. Because the bond is formed between one atom of sulfur (S) and two atoms of oxygen (O) by the sharing of electrons.The difference in electronegativity between sulfur (S) and oxygen (O) atoms on the Pauling scale is not big enough to make an ionic bond in the SO2 compound. So, the covalent bond is present between SO2 molecules.