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Democritus
Democritus used the word ‘atom’ for a definition and realised atoms make up matter. -
Robert Boyle
Robert Boyle gave us a definition of an element. He defined it as any substance, which can be broken up into any amount which is not en element. He also helped with the four elements. -
Antoine Lavoisier
Antoine Lavoisier explained to us that you couldn’t create or destroy a chemical element, just change it into a different compound in chemical reactions. -
John Dalton
John Dalton discovered that the number of atoms characterises the element, tiny particles make up matter, you can’t change atoms and elements react with things, which caused their atoms to combine in ratios. -
Eugen Goldstein
Eugen Goldstein found out the “canal rays” are opposite to an electron. “Canal rays” have electrical and magnetic properties, which are the complete opposite to an electron. -
George Johnstone Stoney
George Johnstone Stoney put the label ‘electron’ on a particle or atom of electricity. -
Joseph John Thomson
Joseph John Thomson suggested atom with positive and negative particles, which he then decided to call electrons. -
Max Planck
Max Planck developed the quantum theory. He also gave us an understanding about why light has a certain form of energy. -
Robert Millikan
Robert Millikan did an oil drop experiment and discovered that electrons charge by themselves. -
Hantaro Nagaoka
Though about the atom and that it had flat rings full of electrons, which are positively charged. -
Ernest Rutherford
Ernest Rutherford told us that the nucleus is charged positively in the atom. He also proved that the atom was space which was empty. -
Henry Moseley
Henry Moseley wrote “The atomic number of an element is equal to the number of protons in the nucleus”. This work helped with the periodic table. -
Neils Bohr
Neils Bohr contributed some more information to the quantum theory about structure of atoms. He explained that electrons can change from one energy level to another. -
Erwin Schrodinger
Schrodinger found out the level of an electron by using mathematics. He also developed a model (quantum mechanics model), which is still accepted in today’s world. -
James Chadwick
James Chadwick discovered the neutron. He did this by alpha particles and discovered something close to a proton.
