If a person is studying matter, its characteristics, and how it interacts with other matter and energy, then that person is studying chemistry. The word "chemistry" came from the word "alchemy," which refers to the set of practices done by people in ancient times that involves chemistry, metallurgy, medicine, astrology, and philosophy. Some references say that the word "alchemy" came from the Arabic word which means "cast together." With this in mind, it can be assumed that chemistry is already practiced since thousand of years ago. In fact, it is said that Egyptians started it around 4,000 years ago.
It was mentioned earlier that chemistry deals with matter and energy. At this point, it is important to note that matter refers to anything that occupies space and has mass, while energy is the capacity of an object or a system to exert effort or force along a certain path. Therefore, chemistry seeks to understand, for example, how heat, which is considered a form of energy, interacts with water, which is matter. Persons who seriously study chemistry are considered chemists.
Chemistry should not be confused with physics. Although these branches of science both study matter and energy, physics studies laws that dominate space and matter. Physics is said to be focused on the nuclear part of the atom and on the subatomic field, and on quantities of space and matter. Physics also deals with motion through space-time. Meanwhile, chemistry deals with the structure, composition, and behavior of matter, and its reactions and interactions with other matter. With that in mind, some principles described in physics are also being applied in chemistry. In fact, the concepts of energy and entropy (which refers to the property that can be used to determine the availability of energy in a system) are frequently used to explain chemical processes and reactions.
Most references say that there are five main branches of chemistry, since this field has a wide scope, just like the other branches of science. These branches are organic chemistry, inorganic chemistry, analytical chemistry, physical chemistry, and biochemistry. Other fields within chemistry include materials chemistry, neurochemistry, nuclear chemistry, marine chemistry, astrochemistry, and molecular biology.
Organic chemistry is fixed on the element carbon. Therefore, anything that deals with this element and its compounds is called organic chemistry. And because living organisms are composed mainly of carbon and its compounds, some references say that organic chemistry is also called the chemistry of life. With that in mind, how does this differ with biochemistry? Biochemistry, on the other hand, focuses on the chemical processes happening inside the bodies of living organisms. This is the reason why, in other references, biochemistry is only considered to be part of organic chemistry. Meanwhile, inorganic chemistry, as the name implies, focuses on non-carbon compounds.
What about analytical chemistry versus physical chemistry? Analytical chemistry concentrates on measuring and determining properties of matter through development of tools, especially those used in laboratories. As the name implies, people involved in analytical chemistry spends time in analyzing the structure and composition of matter through material samples. Meanwhile, physical chemistry involves application of principles of physics. As mentioned earlier, laws that govern matter and energy, which are discussed in physics, can truly be used in chemistry. An example of this is application of the principles of thermodynamics to determine behavior and interactions of matter.
Chemistry may sound boring as it also deals with other sciences especially physics and mathematics. However, studying chemistry can help understand how things work. In fact, this can help understand, for instance, why some substances dissolve faster in warm water, or how medications for stomach pain work. Most, if not all, everyday activities and materials that people use involve chemistry.