Chapter 
1 

Introduction 




Chemistry is everywhere! Everything we can touch or see or smell contains one or more chemicals. From the day of our birth to the day we die, we live in a world of chemicals -many occur naturally, some are synthetic. All of the materials used by engineers and technologists are made by chemical reactions. Over 25 million of chemicals are now known, which is an increase of 5 million in just one year. Chemicals are present in food, medicine, vitamins, paint, glue, cleaning products, building materials, electronic and sporting equipment, and so on. Understanding chemistry is the key to understanding the world as we know it. 
Chemistry is the study of matter and its properties, the changes that matter undergoes and the energy associated with those changes. Chemistry has been traditionally subdivided into four areas: inorganic, organic, analytical and physical chemistry. Inorganic chemistry is the study of properties and behavior of inorganic matter. Organic chemistry studies the structure, properties, composition, reactions and preparation of organic matter. Analytical chemistry is the study of the chemical composition and structure of natural and artificial materials. Physical chemistry focuses on chemical reactions and resolve in the direction and extent of the problem, chemical reaction rate and mechanism of the problem. From the beginning of the 20th century, chemistry has diverse applications and connects other natural sciences, such as astronomy, material science, biology, geology, medicine, agriculture, and many other fields. So chemistry is central to our understanding of other sciences. Chemistry is frequently called the central science and impacts on all facets of our lives. 
Chemistry is closely related to medicine. By the first half of the sixteenth century, the aim of the alchemists had changed from the making of gold to the making of medicines for treating diseases. In 1932, the German bacteriologist Gerhard Domagk discovered that a red dye called prontosil killed certain infectious bacteria. Domagk used sulfanilamide to cure a deadly infection in a ten-month-old infant later, thus launching a revolution in the treatment of infectious diseases. 
Chemicals are the basis for life. Some chemicals can save lives, some can be lethal. Many chemicals are potentially both harmful and helpful. It is how we handle and use them that make the difference. An understanding of the fundamentals of chemistry is essential to the proper handling and use of chemicals. 
Modern medicine is firmly rooted in the chemical nature of the human body. In recent years, the development of molecular biology caused people to know life at the molecular level, and produced huge influences in medicine and other subjects related to biology. One of the largest areas of chemical research today is the development of new pharmaceuticals. Because antibiotic resistance is causing problem when treating many diseases, new drugs are continually being developed. The treatment of the HIV virus has been revolutionized by the use of protease-inhibiting medications. Organic transplants are made possible by the use of anti-rejection medications. Modern medicine would not be possible without chemistry. 


1.2 The Scope of the Book 
General chemistry is an integral and fundamental course for medical students. The course is both at the macroscopic and microscopic level. The purpose of this course is to introduce basic chemical concepts, principles and practical applications of chemistry in medical science. It will enable students to appreciate the importance of chemistry. All these can be helpful for your subsequent courses (organic chemistry, biochemistry, physiology, pharmacy, etc.), work, scientific research and ability training. 
In this edition, we have tried to pay much more attention to the needs of our international students. The book is divided into 5 parts: solution chemistry and colloid, thermodynamics and kinetics of chemical reactions and equilibrium, chemical