I disagree with Lou_86 - Conquering Chemistry is the standard Chemistry text book used by many schools. It is written by Roland Smith, who used to be an academic at Macquarie University. It is not just a study guide. (If you've seen it, it is orange coloured, and includes only three of the electives - Industrial, Forensic and Shipwrecks.) There is also a website that indicates what material is no longer relevant given the syllabus changes that have occurred since 2001.
Of the three standard textbooks (the others being the one by Thickett and the one by Irwin, Farrelly, Garnett and the fourth person whose name I can never remember), it is the one I prefer. This is not to suggest that the others are not adequate / acceptable / good - but if you are using one of the others, and having trouble understansing it / think another text book would help, then Smith is certainly worth considering.