-
300 BC
He stated that all matter is made from the four elements: fire, water, air, and earth. He basically stated that there was no such thing as an atom. -
Published his Atomic Theory which states that all matter is composed of atoms, which are small and indivisible. He stated the first atomic model.
-
He proposed electric and magnetic fields filled the void in the atom.
-
She discovered uranium and thorium and discovered two previously unknown elements: radium and polonium. Which are made of atoms.
-
He discovered three different radioactivity: alpha particles (+), beta particles (-) and gamma rays (neutral). With this information and more test he constructed a new atomic model.
-
He attempts to use x-rays to determine the number of protons in the nucleus of each atom. He was unsuccessful because the neutron had not been discovered yet.