This book provides a clear and structured introduction to quantum mechanics, presenting the fundamental concepts that govern the behaviour of matter and radiation at microscopic scales. It explains the mathematical and physical foundations of quantum theory, linking abstract formalisms with physical interpretation. The discussion explores wave–particle duality, quantisation, and dynamical behaviour of atomic and molecular systems, emphasising how quantum principles differ from classical descriptions. Attention is given to interactions between radiation and matter, energy transitions, and reaction processes governed by quantum laws. By integrating conceptual explanation with analytical reasoning, the book builds a coherent framework that supports understanding of modern physics and its relevance to chemical and physical systems within scientific education, interdisciplinary research, and applied technological contexts globally today in higher learning and professional training.

It is intended for undergraduate students and early researchers in physics and related disciplines. The book serves as an academic foundation and learning guide, supporting conceptual clarity, problem solving, and progression to advanced study in quantum physics and its applications across theoretical, experimental, and interdisciplinary scientific domains within contemporary higher education worldwide contexts today.