Particles & Atoms

Atoms are the tiny particles that make up all matter. Every element is composed of one type of atom, and atoms are too small to see with the naked eye or even an ordinary microscope.

A chemical experiment is a planned investigation that tests a hypothesis using controlled conditions. Learning to design, carry out, and record experiments is a fundamental scientific skill.

Chemistry is not confined to laboratories — it is happening all around you, every moment of the day. From the food on your plate to the screen you are reading this on, chemistry explains how the world works.

The chemistry laboratory is where scientists design and carry out experiments. Understanding its equipment and safety rules is essential before any practical work can begin.

Electrons occupy shells (energy levels) around the nucleus. The arrangement of electrons in these shells — called electronic configuration — determines how an element behaves chemically and reacts with other elements.

An element contains only one type of atom and cannot be broken down into simpler substances. A compound contains two or more different elements chemically bonded together and has different properties from the elements it was made from.

An ion is a charged atom or group of atoms that has gained or lost electrons. When metals and non-metals react, they transfer electrons to form positive and negative ions that attract each other — this is ionic bonding.

Isotopes are atoms of the same element that have different numbers of neutrons. They have the same chemical properties but different masses. Some isotopes are radioactive, while others are stable.

Molecules are formed when two or more atoms bond together. They can be made of atoms of the same element or different elements, and their properties differ from the individual atoms they are made of.

Every atom has a nucleus containing protons and neutrons, surrounded by electrons. The number of protons determines which element an atom belongs to and gives it its chemical identity.

Chemistry is the science of matter — what substances are made of, how they behave, and how they change. It underpins almost everything in the world around us, from the food we eat to the medicines that keep us healthy.