Learning to Name and Write Formulas:

- Determining the type of compound you are working with.

- Applying the rules for naming or formula writing for that type of compound.

- Practicing until it becomes second nature.

How to Write Chemical Formulas for Molecular Compounds

Formula writing for molecular compounds is probably the easiest type of formula writing. The key is memorizing the prefixes. Many of the prefixes you'll be familiar with since they are part of words we frequently use. To be successful writing formulas for molecular compounds, spend some time making sure you know all of the prefixes.

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Rules for Formula Writing for Molecular Compounds

  • Write the element symbol for both elements.
  • Place a subscript after each element according to its prefix.
  • Note: Don't write the subscript '1'.


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