This book, the fourth in a series of Understanding Chemistry books, deals with Basic Chemistry.Written for students taking either the University of Cambridge O-level examinations or the GCSE examinations, this textbook covers essential topics under both stipulated chemistry syllabi. The book is written in such a way as to guide the reader through the understanding and applications of basic essential chemical concepts by introducing a discourse feature — the asking and answering of questions — that stimulates coherent thinking and hence, elucidates ideas. Based on the Socratic Method, questions are implanted throughout the book to help facilitate the reader's development in forming logical conclusions of concepts. The book helps students to master fundamental chemical concepts in a simple way.