Iron is a transition element and has a variable oxidation number so needs to be given an oxidation number. The oxygen will have a -2 charge so the iron must be +2. This is a neutral compound with two elements in it - it is an oxide. The name is iron(II) oxide.

Chromium is a transition element and has a variable oxidation number so needs to be given an oxidation number. The chlorine will have a -1 charge so the chromium must be +3. The name is chromium(III) chloride.

Copper is a transition element and has a variable oxidation number so needs to be given an oxidation number. The sulfate ion will have a -2 charge so the copper must be +2. The name is copper(II) sulfate. Technically, as there is more than one oxidation number possible for the sulfur, it should be called copper(II) sulfate(VI). However, as the SO₄^2- ion is so common it is not usually identified with an oxidation number.

The H atom at the start gives away the identity of an acid. With H = +1 and O = -2, we get an oxidation number of +3 for the nitrogen. Consequently, the Stock notation name is nitric(III) acid. It is more commonly known as nitrous acid.

Manganese is a transition element and has a variable oxidation number so needs to be given an oxidation number. The oxygen will have a -2 charge and the sodium a +1 charge, so the manganese must be +6. We know that the sodium is present as Na+, so there must be a MnO₄^2- ion. This is an oxy-anion and not an oxide, so the name is sodium manganate(VI).

Barium is in group II and only ever has one oxidation number, so this does not need to be stated. This is not an ion and contains just the two elements - it is an oxide. The name is barium oxide.

More H at the start, and another acid. We know that H = +1 and O = -2, so the phosphorus must have an oxidation number of +5. The name is phosphoric(V) acid, although this is the most common phosphoric acid and the oxidation number is often left out.

The 2- charge in the top right hand corner is a bit of a clue that this is an ion! Negative ions which contain oxygen are oxy-anions and the name always ends -ATE. The oxidation number of the oxygen is -2, so the chromium must be +6. This is the chromate(VI) ion.

Manganese is a transition element and has a variable oxidation number so needs to be given an oxidation number. The hydroxide ion will have a -1 charge so the manganese must be +2. The name is manganese(II) hydroxide.

Lead is not in our oxidation number rule list and does have a variable oxidation number. So it needs to be given an oxidation number. The chlorine has an oxidation number of -1, so the lead must be +4. This is lead(IV) chloride.

Copper is a transition element and has a variable oxidation number so needs to be given an oxidation number. The sulfur will have a -2 charge so the copper must be +1. When a single element appears combined with a metal the ending is always -IDE. The name is copper(I) sulfide.

Another H at the start and another acid. You should recognize this formula straight away as nitric acid. As the nitrogen can have a different oxidation number we really should include the oxidation number. With H = +1 and O = -2, we get N = +5. The official name is nitric(V) acid, but the oxidation number is very rarely seen.

We know that calcium is always +2, which makes the other ion PO₄^3-. This is an oxy-anion so will be called phosphate. With O = -2 the phosphorus must be +5. So the name is calcium phosphate(V).

Two elements, one of them oxygen, and no charge. This is an oxide. The vanadium needs an oxidation number as it is a transition element. the name is vanadium(III) oxide.

Take away Na⁺ and you're left with VO₃^-. A negative ion must end -ATE. With the sodium being +1 and each oxygen - 2, the vanadium must be + 5 to give no overall charge. This is sodium vanadate(V).

Take away K⁺ and you're left with IO^-. A negative ion must end -ATE. With the potassium being +1 and the oxygen - 2, the iodine must be + 1 to give no overall charge. This is potassium iodate(I).

Aluminium is always +3, so there is no need for an oxidation number here. This is aluminium chloride.

Take away K⁺ and you're left with CrO₂^3-. A negative ion must end -ATE. With the potassium being +1 and the oxygen - 2, the chromium must be + 3 to give no overall charge. This is potassium chromate(III).

A negative ion indicates that this is a chlorate. The oxygen will be - 2, so four of them give - 8. With -1 left over, the chlorine must be + 7. This is the chlorate(VII) ion.

This looks like an acid with the hydrogen atoms present. H will be + 1 and O will be -2. In order to give no overall charge the selenium must be + 6. This is selenic(VI) acid.