What is Chemistry

Chemistry is the study of matter, its properties, changes in matter and the laws and principles governing it. Chemistry is everywhere around you and it is inevitable, even if you hate it. The air you breathe, the scents you smell, the food you eat, the drugs you take, even you yourself are a splendid example of chemistry. Chemistry studies matter on the macroscopic level and finds the reasons for its properties at the microscopic and submicroscopic levels. 

Chemistry helps to predict properties of matter, as a certain pattern is followed by properties the matter possesses. An example to support the previous line: When all the elements of the periodic table were not yet discovered and the periodic table was not yet invented, Mendeleev, a chemist, invented a periodic table based on atomic masses. He believed that the properties of the elements followed some periodic arrangement and thought that the gaps between the two elements are non-discovered elements. He predicted the properties of an element below Aluminum, which later on was discovered, Gallium, and had almost similar properties as he had predicted.

Preliminaries

Before we further talk about chemistry, we need to put forward some definitions:

Matter

Matter is anything that has mass and occupies space, e.g. air, water, human chair etc.

Property

Property is a characteristic of a substance based on which it is distinguished from other materials e.g. a metal and a non-metal can be distinguished by the property of conductivity(there are many other properties that distinguish metals from nonmetals, conductivity is cited as an example).

Elements

Element is a substance that is made up of the same atoms throughout e.g. oxygen is an element that is made from the same atoms having atomic number 8.

Atoms 

Atoms are infinitesimally small building blocks of elements. To have insight, hydrogen’s atomic radius is 0.529 * 10^-10 m, an average human hair is 5 * 10^-5 m thick and radius of hydrogen is almost a million times smaller than the thickness of a human hair.

Why Study Chemistry?

You may have encountered chemistry as a subject even if you are not a chemistry major. Every field is related to chemistry, be it Biology, Engineering, Medical, Geology, Pharmacology, etc. It is chemistry which helps pharmacists and pharmacologist to produce new drugs, synthesize artificial vitamins and many other supplements. It helps engineers better understand processes on the molecular level e.g. it helps chemical engineers understand processes and how to get maximum production from a certain reaction with particular resources.

In Biology or the Medical field, it helps the doctors or biologists to understand the interior reactions in a living organism, the interaction of the human body with external agents, etc. and to identify substances that are toxic and injurious to the health of a specific organism. It helps Geologists understand how formations form and how the composition of formation affects its structure. This is the reason Chemistry is termed as “The Central Science”.

Who are chemists and what do they do?

Chemists are those people who have a degree in chemistry major. They are employed in many places e.g. as a team member of the research and development team in a chemical industry producing new chemicals(as once Haber produced ammonia with BASF), in a pharmaceutical industry producing new life saving drugs, in an environmental regulatory authority, keeping a check on the carbon emissions in a particular area or may be they are given the job to analyze materials as a quality control  team member. In short, chemists:

1. Produce new chemicals of some desired properties
2. Measure properties of matter
3. Develop mathematical equations to better understand matter at microscopic level as well as macroscopic level.

Classification of matter

Matter is classified based on

1. Its physical state 
2. Its composition. 

Physical State:

Matter is divided into four states of matter on the basis of its physical state i.e. Solid, Liquid, Gas, and Plasma. A gas has no fixed shape or volume and takes the shape of the container. It has the ability to compress and expand. A liquid has a fixed volume but no definite shape. It takes the shape of the container. Solid has a fixed shape as well as volume. Both liquids and gases do not compress to a significant level.

Composition:

Matter is divided into elements, compound, and mixture, based on composition. Before knowing these three, we need to know what is substance. Substance is matter whose properties do not change from sample to sample and has fixed composition. Element, as described earlier, is a substance made up of one kind of atoms. Compound, on the other hand, is a substance made up of the combination of different types of atoms such as water, which is made up of two atoms of hydrogen and a single oxygen atom. Mixture is a mix of different kinds of substances for example salt in water. This has no definitive properties and is a function of composition.