why is Fe2O3 = Iron III oxide
and FeSO4 = Iron II Sulfate
Because the iron is in a differnt valence state in the two different compounds. With iron sulfate, iron donates two electrons to the sulfate ion, and with iron oxide it donates or shares three electrons per iron atom with the oxygen atoms.
Fe2 O3
Fe is iron, and O is oxygen. When the second part is an element, then take off the ending and add -ide.
Switch the 2 and 3, and you should have your answer. It's not necessary to write the roman numeral unless the element can have more than one number of valence electrons. You can reference a periodic table.
Fe2 O3
Write out Fe and O.
iron+2 oxygen-3
Switch the numbers, disregarding the positive/negative.
iron3 oxygen2
Change oxygen to oxide because the second part (anion) is an element.
iron3 oxide2
Write with Roman numerals, and drop O's number because it has only one.
iron(III) oxide
The second one is similar, but SO4 is a polyatomic ion, so you'll have to reference the chart in your book to see its corresponding empirical form.
Fe2O3 is called iron(III) oxide because it contains iron in its +3 oxidation state. The name iron(III) indicates that iron is present in its +3 oxidation state, and oxide indicates the presence of oxygen.
To determine the oxidation state of iron in Fe2O3, we can use the fact that the overall charge of a compound is zero. Since oxygen usually has an oxidation state of -2, we can set up the equation:
2x + 3(-2) = 0
Simplifying the equation gives:
2x - 6 = 0
2x = 6
x = 3
Therefore, iron in Fe2O3 is present in its +3 oxidation state, leading to the name iron(III) oxide.
Similarly, FeSO4 is called iron(II) sulfate because it contains iron in its +2 oxidation state. The name iron(II) indicates that iron is present in its +2 oxidation state, and sulfate indicates the presence of the SO4 2- polyatomic ion.
To determine the oxidation state of iron in FeSO4, we can use the same approach:
x + 1(-2) + 4(-2) = 0
Simplifying the equation gives:
x - 2 - 8 = 0
x - 10 = 0
x = 10
But since iron only has oxidation states of +2 and +3 in most common compounds, we conclude that iron in FeSO4 is present in its +2 oxidation state, leading to the name iron(II) sulfate.