Those who are studying chemistry and in need of serious help should check this page: Useful websites recommended by CIE.
It’s not only helpful for those taking CIE syllabus, but you may find it tailored for the syllabus. Some of the websites requires understanding and sound vocabulary on chemistry vocabulary.
At the most important note, they are in English so Indonesian students may find the contents rather challenging when the terms are not too close with what had been introduced in class.
Still, it is worthy to look at. Goes to my favourites.