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400 BCE
Democritus
He developed the concept of an atom and believed that everything on Earth was made up of them. He believed that atoms were indivisible and indestructible. -
John Dalton
He discovered that all matter was composed of atoms. He published a theory that an element is composed of only one kind of atom, and a compound is composed of particles that are chemical combinations of different kinds of atoms. -
Dmitri Mendeleev
Created the first Periodic Table -
Eugene Goldstein
He discovered canal rays with positive particles and named them protons. -
J.J. Thomson
Examined two ways that a cathode ray can be deflected using a magnet and using electronically charged plates. With that, he discovered the electron. -
Ernest Rutherford
With his gold foil experiment, he demonstrated that an atom has a tiny and heavy nucleus -
Niels Bohr
He was the first to discover that electrons travel in separate orbits around the nucleus -
Max Planck
Originated the Quantum Theory which explains the nature and behavior of matter and energy on the atomic and subatomic level -
Werner Heisenberg
He is known for his uncertainty principle and theory of quantum mechanics -
Erwin Schrodinger
Used mathematical equations to describe the likelihood of finding an electron in a certain position -
James Chadwick
He discovered the Neutron in atoms.
