Part V — Chapter 13
Radioactivity & Atomic Structure
The discoveries that opened the door to the subatomic world
13.1 X-Rays and Radioactivity
In 1895, Wilhelm Röntgen discovered X-rays. Within months, Henri Becquerel found that uranium emits penetrating radiation spontaneously. Marie and Pierre Curie isolated radium and polonium, coining the term "radioactivity."
13.2 Rutherford's Nuclear Atom
Ernest Rutherford (1871–1937) directed alpha particles at gold foil and discovered that the atom has a tiny, dense nucleus. He identified alpha, beta, and gamma radiation and achieved the first artificial nuclear transmutation in 1919.
Great Physicists: Niels Bohr — Father of Atomic Physics
13.3 Lise Meitner & Nuclear Fission
Lise Meitner (1878–1968) provided the first theoretical explanation of nuclear fission in 1939. Despite her critical role, the Nobel Prize went to Otto Hahn alone — one of the most controversial omissions in Nobel history.