In this video we'll write the correct formula for Iodine heptafluoride (IF7).

To write the formula for Iodine heptafluoride we’ll use the Periodic Table and follow some simple rules.

When we have a non-metal and a non-metal we have a molecular compound (sometimes called covalent). Molecular compounds are some of the simplest to name.

Keys for Writing the Formulas 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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Prefixes
mono- 1
di- 2
tri- 3
tetra- 4
penta- 5
hexa- 6
hepta- 7
octa- 8
nona- 9
deca- 10
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Caution: We only write "mono" for the second element in a molecular compound. So CO would be carbon monoxide. Monocarbon monooxide is incorrect.

For a complete tutorial on naming and formula writing for compounds, like Iodine heptafluoride and more, visit:

http://www.breslyn.org/chemistry/naming

Drawing/writing done in InkScape (https://www.InkScape.org). Screen capture done with Camtasia Studio 4.0. Created on a Dell Dimension laptop computer with a Wacom digital tablet (Bamboo).