Atomic Structure

What is Atomic Structure?

Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains Atomic Structure. Chemistry links what you can see in the lab to the particles and bonds behind it, so each topic here shows that link in a model.

Check that you can explain Atomic Structure in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

Understanding Atomic Structure helps you explain why substances behave as they do, from cleaning products and food to medicines.

Atomic Structure in detail

An atom consists of a small, dense nucleus containing protons (relative charge +1, mass 1) and neutrons (charge 0, mass 1), surrounded by electrons (charge −1, negligible mass) in shells. Atoms are neutral because the numbers of protons and electrons are equal.

The atomic number is the number of protons, which defines the element, and the mass number is the sum of protons and neutrons. The radius of an atom is about 0.1 nm, and the nucleus is about 10,000 times smaller. Atomic structure explains the periodic table and chemical bonding.

How the interactive helps you understand Atomic Structure

Watch the atom model in the interactive. Use any sliders or buttons it offers to change the values and see how the atom model responds.

Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Atomic Structure.

Real-life uses and examples

• Use Atomic Structure to explain what happens in a lab experiment and why.
• Link Atomic Structure to everyday products such as cleaning agents, food and medicines.
• Read a chemical equation or diagram and work out what Atomic Structure shows.

Common mistakes to avoid

• Describing what happens without explaining the particles or bonds involved.
• Mixing up the names of substances or ions when you describe Atomic Structure.
• Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.