10 Basic Concepts of Chemistry

by Kate Onissiphorou

Chemistry studies phenomena that can be precisely represented in mathematical forms and demonstrated in practical ways. For example, you can calculate the reactions between sodium hydroxide and hydrochloric acid using the respective molar masses of the acidic and basic solutions. You can then use these calculations to obtain precise amounts of products.

Like other physical sciences, chemistry is anchored on predictable laws and well-established theories. From elements to complex organic compounds, these laws and theories are reliable guides for chemists, providing them with the necessary intellectual tools to do their job effectively.

Foundational knowledge of chemistry is vital if you intend to pursue a career in this field. Whether you want to become a chemistry teacher or an industrial research chemist, you’ll first need to have a good grasp of the basic concepts of chemistry.

1. What is chemistry?  An illustration of chemistry beakers

Chemistry is a physical science that focuses on the study of substances (chemical elements and compounds), their properties, behaviours, structures and applications.

While ancient civilisations had some inkling about the differences between elements and compounds, the real science of chemistry began as a product of the Age of Enlightenment. It was at this point that scientific methods were developed based on empiricism and rationalism rather than supernaturalistic ideas.

Over time, chemistry has gradually become a specialised scientific discipline with its own branches. 

2. Why is chemistry important?

Chemistry as a process has been ongoing since the first elements were formed inside the nuclear furnaces of stars. When the stars died in massive explosions as supernovas, they seeded space, and eventually planets, with the ingredients for life.

From the nuclear chemistry inside stars to the biochemistry inside living organisms, chemistry as a process makes the universe function like a complex machine. 

Chemistry as a scientific discipline helps us to better understand the universe and ourselves. Its many applications allow us to have everyday conveniences, such as food, clothes, vehicles and medicines.

3. What are the types of chemistry?

Chemistry is a physical science. This means it does not deal with living organisms, although the demarcation becomes blurred when it comes to biochemistry. There are various types or branches of chemistry. These include:

4. What is an atom?

Atom molecule as concept for science

An atom is the smallest fundamental unit of particles and is responsible for the chemical identity of a substance.

At its centre is the nucleus, which contains protons and neutrons. The number of protons determines the type of element, while the combination of protons and neutrons determines the atomic mass. Clouds of electrons at different orbitals surround the nucleus.

The reactions among the elemental atoms form chemical molecules, which in turn form all the macroscopic objects, including living organisms.

5. What is a molecule?

A molecule is a combination of two or more atoms that are chemically bonded, for example, an ionic or covalent bond. Even elements can form molecules, such as the seven diatomic elements, which are hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), chlorine (Cl), bromine (Br) and iodine (I).

Molecules can form chains and rings, as well as geometric shapes like a tetrahedral.

6. What types of chemical compounds are there?

Chemical compounds are generally categorised based on the type of bonds that hold the atoms together and form the molecules. A compound can be ionic like salts or covalent like sugars. Compounds can also be classified as either organic or inorganic.

Organic compounds contain carbon as the backbone atom, while inorganic compounds may contain carbons but they are not the central element.

7. What is the periodic table? Diagram of the periodic table

The periodic table of chemical elements is a systematic and organised collection of information about the elements arranged by their periodicity.

Chemical elements are also arranged according to their group properties, for example, the noble gases. Each entry contains key information including the atomic number, atomic weight, electron configuration, and electronegativity.

8. What are acids and bases?

Acids and bases are chemically opposite in terms of their pH values.

On a logarithmic scale of 0 to 14, acids have pH values below 7 and bases have pH values above 7. There are three theories that explain how acids and bases work:

  • The Arrhenius theory
  • The Brønsted-Lowry
  • The Lewis electron-pair theory

Generally, in a neutralisation reaction, an acid donates a proton while a base accepts the proton. The chemical reaction between acids and bases is known as neutralisation because the resultant products are neutral salts and water.

9. What is conjugation?

In organic chemistry, conjugation describes the overlapping of p-orbitals with delocalised electrons in a molecule. Some of the practical products of conjugation include conductive polymers and carbon nanotubes.

10. Different chemical changes

Chemical changes are classified according to how the constituents of substances interact and rearrange themselves when reacting with each other. The five general types of chemical changes are:


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