Predicting the Formula of Ionic Compound
- We can predict the charge of the ions formed from an element base on the group of the element.
- From the charge, we can then write the formula of the ionic compound formed.
- In short, we can predict the formula of an ionic compound if we know the group (in the periodic table) of the elements in the compound.
- The table below shows the formula of the ionic compounds formed by the elements from different group in a periodic table.
Elements | Formula of Ionic Compound | Examples | |
| Atoms of Metal, M | Atoms of Non-Metal, N | ||
Group 1 | Group 15 | M3N | Na3N |
Group 1 | Group 16 | M2N | K2O |
Group 1 | Group 17 | MN | LiCl |
Group 2 | Group 15 | M3N2 | Ca3N2 |
Group 2 | Group 16 | MN | MgO |
Group 2 | Group 17 | MN2 | BaBr2 |
Group 13 | Group 15 | MN | AlN |
Group 13 | Group 16 | M2N3 | Al2O3 |
Group 13 | Group 17 | MN3 | AlI3 |