How to Write the Formula for Iron (II) phosphide

In this video we'll write the correct formula for Iron (II) phosphide (Fe3P2).

To write the formula for Iron (II) phosphide we’ll use the Periodic Table and follow some simple rules.

---Keys for Writing Formulas for Compounds with Transition Metals---

1. Write the symbol and charge for the transition metal. The charge is the Roman Numeral in parentheses.
3. See if the charges are balanced (if they are you're done!)
4. Add subscripts (if necessary) so the charge for the entire compound is zero.
5. Use the crisscross method to check your work.

Notes:
- Don't write the subscript '1'.
- If you use the criss-cross method and end up with something like Ca2S2 you'll need to reduce the subscripts to Ca1S1 which we write CaS.
- It is possible to have two polyatomic ions such as NH4NO3. In this case find and write both names as found on the Common Ion Table.
For a complete tutorial on naming and formula writing for compounds, like Iron (II) phosphide and more, visit:

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

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