1895 Wilhelm Röntgen investigates the properties of X-rays.
1896 Henri Becquerel discovers that uranium salts emit penetrating radiation.
1897 J. J. Thomson discovers the electron while exploring the properties of cathode rays.
1904 Thomson proposes the “plum pudding” model of the atom.
1911 Ernest Rutherford and Ernest Marsden propose the “nuclear model” of the atom.
1932 British physicist James Chadwick discovers the neutron.
Like many major scientific discoveries, radiation was found by accident. In 1896, French physicist Henri Becquerel was investigating phosphorescence, which occurs when light falls on a substance ...