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Newton
Proposed a mechanical universe with small solid masses -
Dalton
All matter is made of atoms. Atoms are indivisible and indestructible. All atoms of a given element are identical in mass and properties. Compounds are formed by a combination of two or more different kinds of atoms. A chemical reaction is a rearrangement of atoms. -
G.J. Stoney
Introduced/suggested the concept of an “electron” to describe the fundamental unit of electrical charge -
J.J. Thomson
Discovered the electron . Believed that atoms were divisible and corpuscles were their building blocks. Demonstrated that hudrogen had only a single electron per atom. -
Planck
Energy, instead of being continuous, comes in distant particles. “quanta” -
Nagaoka
Developed an early, incorrect “planetary model” of the atom. Based around an analogy to the explanation of the stability of the Saturn rings. -
Milikan
Able to successfully measure the charge on a single electron. -
E. Rutherford
Devised the planetary model in which a number of tiny electrons circled the nucleus like planets around the sun. -
H.G.J. Mosely
Redefined the idea of atomic number from its previous status as an ad hoc numeral tag to help sorting the elements, in particular, the Periodic Table, into a real and objective whole number quantity that was experimentally measurable. -
Bohr
Devised a model in which the electrons orbited the nucleus, the chemical properties of the elements being largely determined by the number of electron in the outer orbits. -
James Chadwick
Discovered the neutron. Was known as the neutron because of lack of electrical charge. He helped build the atom bomb.