This book is the revised edition of Understanding Basic Chemistry Through Problem Solving published in 2015. It is in a series of Understanding Chemistry books, which deals with Basic Chemistry using the problem solving approach. Written for students taking either the university of Cambridge O-level examinations or the GCSE examinations, this guidebook covers essential topics and concepts under both stipulated chemistry syllabi. The book is written in such a way as to guide the reader through the understanding and applications of essential chemical concepts using the problem solving approach. The authors have also retained the popular discourse feature from their previous few books -- Understanding Advanced Physical Inorganic Chemistry, Understanding Advanced Organic and Analytical Chemistry, Understanding Advanced Chemistry Through Problem Solving, and Understanding Basic Chemistry -- to help the learners better understand and see for themselves, how the concepts should be applied during solving problems. Based on the Socratic Method, questions are implanted throughout the book to help facilitate the reader's development in forming logical conclusions of concepts and the way they are being applied to explain the problems. In addition, the authors have also included important summaries and concept maps to help the learners to recall, remember, reinforce and apply the fundamental chemical concepts in a simple way.