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Oxygen
Joseph Priestly was able to classify the type of air known as oxygen. In his experiments he was able to produce oxygen and clarify his findings with Antoine Lavoisier. -
Atomic Theory
John Dalton discovered that atoms, while not visible to the human eye, could be measured and quantified. Pure elements contained the same atoms, with the same mass. He called this the atomic theory. -
Electricity Transforms Chemicals
Humphrey Davy discovered that you can transform chemicals by using electricity. Using an electric pile, he was able to separate salts through what is now called electrolysis. He then able to separate other elements as well. -
Atoms Combine Into Molecules
Amedeo Avogadro discovered that atoms combined with each other to create molecules. He also said that if the temperature, pressure, and volume were the same in gases, that the amount of molecules would also be the same. -
Synthesis of Urea
Friedrich Wohler synthesized urea from using only inorganic materials. This was significant because it meant that living things could be reproduced without using only other living things. -
Atoms Have Signatures of Light
Gustav Kirchhoff and Robert Bunsen discovered that elements absorb and emit light and certain wavelengths, creating specific spectra. -
Chemical Structure
Friedrich Kekule used symbols to represent atoms. Then he added marks to show how they bonded with each other. Benzene wouldn't fit however, but he found a way to represent it by showing it in a ring structure, representing how carbon atoms can bond with up to four other atoms at a time. -
Periodic Table of Elements
Dmitri Mendeleev found that all of the 63 known elements could be arranged in order of atomic weight, and that their properties would be repeated depending on the periodic cycle. -
The Electron
J.J. Thompson discovered what is now known as the electron. He found that they were negatively charged particles emitted by cathode ray tubes and were smaller than atoms. -
Electrons for Chemical Bonds
Niels Bohr created a model to represent atomic structure which showed the electrons. He found that an element's chemical properties were mainly determined by the number of electrons in its orbit.