The Atom
Our knowledge of the atom and it's development through time.
Today's Atomic Model
In today's model, electrons are in constant motion around the nucleus, protons and neutrons move within the nucleus, and quarks move within the protons and neutrons.
John Dalton... 1803
Dalton proposed an "atomic theory," which stated that elements consisted of atoms that were identical and had the same mass and that compounds were atoms from different elements combined together.
J.J. Thompson... 1904
Thomson proposed that there were negative charges embedded in the nucleus, which was positive. The negative charges he called electrons.
Rutherford... 1911
Rutherford conducted the well known gold foil experiment to overturn Thomson's model. He used radioactive charges to discover that the atom has a tiny heavy nucleus that consisted of positive and negative charges- protons and NEUTRONS. Not electrons. They instead orbited around the nucleus in a pattern, such as above.
Niels Bohr... 1913
Bohr proposed that the electrons must move in stable orbits around the nucleus of the atom, as if they moved in the way Rutherford proposed, it would make the atom unstable.