Describe the bonding in, and the structure of, sodium chloride and ice. Explain why they have very different melting points.
(Firstly, we identify this as a ‘Structure and Bonding’ problem and try to distinguish between the bonds holding atoms together and the intermolecular forces holding molecules together. We can take each compound and describe it separately and then compare them at the end.)NaCl has strong ionic bonding (electrostatic force of attraction) between the Na+ and the Cl- ions and is found in a giant ionic lattice, cubic lattice.Ice (water) is made of H2O molecules, with the H and O being held together by strong covalent bonds. The structure of the molecules are V-shaped. The H2O molecules are held together by Hydrogen bonds (as well as Van der Waals interactions).More energy is required to break the many ionic bonds in the giant ionic lattice than to break the weaker Hydrogen bonds between the H2O molecules. More energy to break bonds, means more thermal energy hence higher temperature, hence NaCl has a much higher melting point than ice.
