Groups and Periods

What is Groups and Periods?

Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains Groups and Periods. 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 Groups and Periods in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

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

Groups and Periods in detail

Vertical columns in the periodic table are groups, and elements in a group have the same number of outer-shell electrons and so similar chemical properties. Horizontal rows are periods, and the period number shows the number of occupied electron shells.

Across a period, properties change from metallic to non-metallic. Down a group, atoms get larger because they have more shells, which changes reactivity: Group 1 metals become more reactive down the group, while Group 7 halogens become less reactive. These trends allow chemists to predict how unfamiliar elements will behave.

How the interactive helps you understand Groups and Periods

Click a card to flip it and reveal the answer, then move on to the next one.

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 Groups and Periods.

Real-life uses and examples

• Explain Groups and Periods in an exam by linking the particles involved to what you observe.
• Use Groups and Periods to explain what happens in a lab experiment and why.
• Link Groups and Periods to everyday products such as cleaning agents, food and medicines.

Common mistakes to avoid

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