I suggest reading three books: inorganic chemistry, basic organic chemistry and physical chemistry.

Inorganic Chemistry is a book published by Higher Education Press in 2006 and compiled by the Inorganic Chemistry Department of Dalian University of Technology. At present, it is the fourth edition, including elemental chemistry, thermodynamics, kinetics, material structure, coordination chemistry, electrochemistry and so on.

Basic Organic Chemistry is a book edited by Mr. Xing in 2005 and published by Higher Education Press. This book is the most important foundation of organic chemistry!

Physical Chemistry is a book published by Higher Education Press 20 1 1. Covering the subject of physical chemistry is helpful for the competition.