radioactivity

Everyday

1. Radioactivity is the giving off of invisible energy, called radiation, by the centres (nuclei) of some unstable atoms as they break down. tree →
2. Radioactivity is also a measure of how much of this radiation something gives off. tree →

In the lessons

In science lessons it is introduced with Marie Curie, who studied it and won two Nobel Prizes, with uranium and radium, nuclear power stations, X-rays and safety signs (the yellow trefoil). In everyday life small amounts of radioactivity are all around us naturally, even in bananas and rocks; large amounts are dangerous. Phrases: «levels of radioactivity», «measure radioactivity», «natural radioactivity».

Examples

• Marie Curie studied radioactivity and discovered radium and polonium. tree →
• A Geiger counter clicks when it detects radioactivity. tree →
• High levels of radioactivity can damage living cells. tree →
• Bananas have a tiny, harmless amount of radioactivity. tree →
• After the Chernobyl accident, radioactivity spread over a wide area. tree →
• Scientists use radioactivity to date very old objects. tree →
• The yellow warning sign means radioactivity is present. tree →

Note

Uncountable. Adjective: radioactive. Radioactivity is not the same as radio waves; radios use a harmless kind of wave. Myth: radioactive things do not glow green like in cartoons.