question archive To write this formula, know that the roman numeral in iron (II) simply denotes that this ion of iron has a ##2+## charge
To write this formula, know that the roman numeral in iron (II) simply denotes that this ion of iron has a ##2+## charge
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To write this formula, know that the roman numeral in iron (II) simply denotes that this ion of iron has a ##2+## charge. So, the iron here will be ##Fe^(2+)##
Oxygen ion always has a ##2-## charge since all Group A are monatomic ions - ions of atoms which have only one charge. So oxygen will always be ##O^(2-)##
You can use this guide for predicting the charges of ions:
Now to write the formula is to simply let the charges of each be the subscript of the other and neglecting their signs. Like this:
Now by doing this, you'll end up with a formula unit ##Fe_2O_2##. However, in writing formula units ##-## chemical formula for , we always write the lowest ratio of atoms that we have. Since you have 2 iron ions and 2 oxygen ions, their ratio is 1:1 and therefore we write the formula as ##FeO##.
