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400
Democritus
400BC- His greatest contribution to the atomic theory was being able to determine that the theoretically smallest possible particle is an Atom, which means indivisible in greek, as well as composing the atomic theory in the first place along with Leucippus, his teacher. -
Robert Boyle
Boyle contributed to physical theory, supporting an early form of the atomic theory of matter, which he called the corpuscular philosophy, and using it to explain many of his experimental results.(the philosophy that attempts to account for the phenomena of nature by the characteristics (such as motion, figure, rest, position) of minute particles of matter. -
Antoine Lavoisier
He wrote the first extensive list of elements, and gave us our first look on what an atom really is. Antoine Lavoisier proved the law of conservation of mass around the year 1789. The law of conservation of mass states that: Mass cannot be created or destroyed The mass of the reactants must equal the mass of the products -
John Dalton
He created the atomic theory which is:
1.All matter consists of tiny particles
2.Atoms are indestructible and unchangeable
3.Elements are characterized by the mass of their atoms
4.When Elements react, their atoms combine in simple, whole-number ratios -
Dmitri Mendeleev
He arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law. -
Eugen Goldstein
He used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron. -
J.J. Thomson
He discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode ray tube. -
Ernest Rutherford
The Rutherford model of the atom was simplified in a well known symbol showing electrons circling around the nucleus like planets orbiting the sun. This symbol became popular and has been used by various organizations around the world as a symbol for atoms and atomic energy in general. -
Robert Millikan
He discovered that electrons had charges either positive or negative. -
Niels Bohr
Niels Bohr's greatest contribution to modern physics was the atomic model. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. -
Henry Moseley
He is known for his establishment of truly scientific basis of the Periodic Table of the Elements by sorting chemical elements in the order of their atomic numbers. -
Max Planck
He Initiated quantum theory which ultimately explains the construct of energy states in atoms. -
Erwin Schrodinger
He took the Bohr atom model one step further. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. -
James Chadwick
He discovered the Neutron, of which he feverishly looked for over the span of a decade.
