In third year, the chemistry course covers both Level 4 and Level 5 CfE experiences and outcomes- this includes materials which can be found under National 3,4 5 chemistry. The websites below have good resources which can be valuable to consolidate your class notes and tests.
For revision notes and practice assessments.
For notes and practice tests- bbc knowledge and learning
Other useful website for notes and revision questions
Leckie and Leckie and Hodder Education have published Practise Papers, Success Guides and Student books for both National 4 and 5. Available in Amazon, Waterstones etc.