Describe how to write a formula for a covalent compound Method to deduce the formulae of covalent compoundsNon-metals combine with non-metals to form covalent compounds. Table shows the number of electrons needed by an atom of a non-metal to achieve a stable noble gas electron arrangement. The number of electrons needed is a measure of the combining power of the … [Read more...] about Describe how to write a formula for a covalent compound