The Discovery of Radioactivity Explained Simply

  1. In 1896, Henri Becquerel discovered radioactivity while studying phosphorescent uranium salts.
  2. He noticed photographic plates fogged even without sunlight, proving uranium emitted invisible rays.
  3. These mysterious rays were different from X-rays, discovered only a year earlier.
  4. Marie and Pierre Curie expanded Becquerel’s work, coining the term radioactivity.
  5. They discovered new radioactive elements, polonium and radium, in 1898.
  6. Radioactive materials release energy from the nucleus, not just from chemical reactions.
  7. Early experiments showed radioactivity could penetrate solids and ionize air.
  8. At first, scientists thought radiation might be useful in medicine—and radium was added to tonics and products.
  9. Later, they realized the serious health risks of long-term radiation exposure.
  10. Today, radioactivity is harnessed safely in medicine, energy, and research—thanks to these early pioneers.