Hi, you mention here that all molecules are 'held together by covalent bonds'. Aren't ionic and metallic bonds molecules too? Would you classify NaCl as a molecule or Al2O3 as molecule?
Hi Aditya - a molecule is a particle with 2 or more atoms - in other words it has to have a set number of atoms. Both ionic and metallic structures are giant structures so can go on infinitely and don't count as molecules. The numbers in the formula eg Al2O3 just tell you the ratio of Al:O in the giant structure and doesn't mean there's only 2 Al and 3 Os
