In this video we'll write the correct formula for Sodium aluminum sulfate : NaAl(SO4)2.


To write the formula for Sodium aluminum sulfate we’ll use the Periodic Table, a Common Ion Table, and follow some simple rules.

Because Sodium aluminum sulfate has a polyatomic ion (the group of non-metals after the metal) we'll need to use a table of names for common polyatomic ions, in addition to the Periodic Table.

Keys for Writing Formulas for Ternary Ionic Compounds:
1. Write the element symbol for the metal and its charge using Periodic Table.
2. Find the name and charge of the polyatomic ion on the Common Ion Table (see [ Ссылка ]).
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.

Note: 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.

---Formula Writing Resources---
Finding Ionic Charge: [ Ссылка ]
Memorizing Polyatomic Ions: [ Ссылка ]
Criss-Cross Method: [ Ссылка ]

For a complete tutorial on naming and formula writing for compounds, like Sodium aluminum sulfate and more, visit:

[ Ссылка ]

Drawing/writing done in InkScape. Screen capture done with Camtasia Studio 8.0

свернуть