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Period: 360 to
History
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470
Democritus
Democritus believed that everything is made of atoms. Which are indivisible. Between atoms lies empty space, atoms cannot be broken or destoyed.Atoms will always be in motion and that there are an infinite number of them. -
Antoine Lavoisier
Antoine Lavoisier came up with the theory of converstion of mass. This showed that matter couldnt be created or destroyed. He also showed that compounds are just atoms put together.
Date Adopted: Late 18th Century -
John Dalton
John Dalton put both Democritus and Lavoisier work together. This theory stated that all matter is made of indivisible and indestructible atoms. All atoms of a given element are identical, compounds are the combinations of elements. The last thing he noticed was that a chemical reaction is just a rearrangement of atoms.
Date Adopted: 1803 -
Henri Becquerel
Henri Becquerel discovered radioactivity in his research of uranium and other materials. It determined that researching atoms were a big deal and atoms were affected and can be changed.
Date Adopted: 1896 -
J.J. Thomson
J.J. Thomson did an expirment and when he looked at his findins he found as evidence of much smaller particles, which he called electrons. Using this he made the plum pudding model, which he added the negatively charged electrons.
Date Adopted: 1898 -
Max Planck
Max Planck created the quantum theory. Which was used by many scientists laster to develop their interpertations and models.
Date Adopted: 1900 -
Marie and Pierre Curie
Marie and Pierre Curie made the understanding of radioactivity much better through their research of radioactive materials.They discovered radium and polonium. This showed what happened when atoms were affected and observed.
Date Adopted: 1898 -
Robert Millikan
Robert Millikan discovered the exact charge of the electron, Which helped out J.J Thompson model and so made him right,
He had help on this experiment and that was Harvey Fletcher.
Date Adopted: 1908 -
Ernest Rutherford
Ernest Rutherford did an expirment and with his results formulated the planetary model, which showed that most of the mass of an atom was concentrated in the center. Was trying to prove J.J Thompson but ended up disproving him also he was a student of J.J Thompson.
Date Adopted: 1909 -
Niels Bohr
Niels Bohr stated that electrons had certain amounts of energy using the Quantum theory. He made a new model of the atom where the electrons are around the nucleus in orbits determined by their energy levels. Looked up to Ernest Rutherford.
Date Adopted: 1913 -
Erwin Schrodinger
Erwin Schrodinger introduced the Schrodinger equation, which allowed the motion of the electron to be determined more accurately. This helped Bohr model be more precise. Schrodinger succeeded Max Planck at the Friedrich Wilhelm University.
Date Adopted: 1926 -
Henry Mosely
Henry Moseley is best known for Moseley’s Law. This law states that there is a relationship between the energy of a given element and its atomic number. It supported the peroidic table and Bohr’s model of quantized energy.
Date Adopted: 1915 -
James Chadwick
James Chadwick discovered the neutrally charged neutron in the atom. He made Bohr’s model better by adding neutrons to the nucleus. Also in this discovery he led to the atomic bomb. Chadwick studied under Rutherford in college.
Date Adopted: 1931 -
Werner Heisenberg
Werner Heisenberg created the uncertainty principle, which made Bohr’s model not so great. He kept the idea of quantized energy in electrons, but took away the ability to guess where they will be. Heisenberg looked up to Max Planck.
Date Adopted: 1927 -
Aristotle
Aristole said that atoms were made up of four things water, fire, air, and earth. Each atom had its own special properties depending on what they were made out of. They could be made out of hotness, dryness, coldness, and wetness.
