Molecular Compounds: Chemical Formulas and Naming (Section 7.4 pg 192-196)

Molecular compounds form covalent bonds, so we don’t pay as much attention to ion charges – there are different rules for naming & writing them. We are going to use a lot of prefixes: Don’t worry about memorizing these – they’re in the Data Pages!!!

To write the name of a molecular compound from the formula, follow these steps: Make sure both elements are non-metals. Write the name of the first element with the correct prefix (please note – if there is only ONE atom of the first element, do not use ‘mono’ e.g. CO2 = carbon dioxide) Write the name of the second element with the correct prefix. Change the ending of the second element to -ide. For example, C4S7 = tetracarbon heptasulfide

To write the formula from the name, you simply write down the symbol for each element and then write an appropriate subscript for the number of the prefix for each element. For example, triphosphorus octafluoride = P3F8