History of Chemistry

Democritus

460 BCE

Democritus was a scientist and philosopher from ancient Greece. He experimented with minerals and believed that the universe was created by collisions of atoms. He concluded that everything is composed of indivisible, indestructible atoms. He also proposed that in between atoms, there is empty space. Democritus thought that atoms were always in motion and the shape of an atom corresponds with the material that the atom is making up. He laid the foundation for future atomic theories.

Aristotle

384 BCE

Aristotle was a famous scientist and philosopher from ancient Greece. His main contribution to science was his proposition of the five elements of life- earth, water, air, fire, and ether. He also contributed ideas of substances, potentiality, and actuality. Aristotle defined motion and its causes, as well as classified living things.

Abu Musa Jabir ibn Hayyan

721

Jabir ibn Hayyan lived in Persia, which is now present-day Iran. He described aspects of substances using factors like heat, coldness, moistness, and dryness. He also described the formation of substances and classified chemical properties, especially those of metals and nonmetals. Jabir created the mercury sulfur theory and segregated alloyed metals.

Albert Magnus

1250

Magnus lived in Germany and was a philosopher, alchemist, and astrologist. He is credited with the discovery of arsenic and experimented with photosensitive chemicals. He believed all natural things were made of "matter and form".

Printing Press

1440

The printing press was created by Johannes Gutenberg in Germany in 1440. It did not directly discover anything for chemistry, but it allowed for ideas to be published and spread much more easily and resulted in an increase in information.

Vacuum tube and electric generator

1654

Otto von Guericke was a German scientist and inventor. He is credited with the creation of a vacuum pump and he performed many experiments with them. He allowed for many chemists in future generations to use his invention to make new discoveries.

Robert Boyle

1662

Robert Boyle was a scientist from England. He is most well known for his law, which states that the volume of gas varies inversely with pressure. He defined reality in terms of particles and motion, in contrast to older scientists who defined it in elements of life (like Aristotle). He also conducted experiments that established necessities of things such as combustion and the transmission of sound.

Henry Cavendish

1766

Cavendish was a scientist from England. He determined the value of the universal constant of gravitation. He also discovered hydrogen and was able to measure the density of it. Cavendish researched combustion and composition of materials, as well as CO2 and solubility.

Lavoisier

1785

Lavoisier was a scientist from France. He forever changed the field of science from qualitative to quantitative. He also helped to construct a list of elements and the metric system. He is most well known for his Law of Conservation of Mass, which states that matter may change form of shape but the mass stays the same. He also created a theory about combustion.

Dalton

1803

Dalton was a scientist from England. He experimented to see if the combination of elements occurs in a sequence, and he calculated atomic weights from the percent composition in compounds. Dalton also discovered that all atoms of an element are identical and different atoms have different sizes and different masses. His atomic theory proposed that all matter was composed of atoms and that atoms are not created or destroyed in chemical reactions.

Avogadro

1811

Avogadro was an Italian scientist. He is credited with defining the SI unit of the mole with a number that became known as Avogadro's constant. He also stated that the relationship between masses of volume and gas corresponds to the number of molecules and atomic masses. The same volume of gas is proportionate to the number of molecules. This became known as Avogadro's hypothesis.

Mendeleev

1869

Mendeleev was a Russian scientist. He is most well known for his contributions to the periodic table. He noticed patterns in the elements and arranged them according to atomic weight and valence, He put all the elements (that were known at the time) into the table and also discovered properties of the elements.

William Ramsay

1892

William Ramsey was a scientist from Scotland. He determined the molecular weights of substances. He also discovered argon, helium, neon, krypton, and xenon. However, his largest contribution to chemistry was his introduction of noble gases into the periodic table.

JJ Thomson

1897

JJ Thomson was a British scientist. He calculated the charge to mass ratio of electrons in an atom and attempted to estimate the number of electrons in an atom. He also experimented in a vacuum tube. He suggested the atom as a positive matter sphere with electrons positioned by forces. This became known as the "plum pudding" model. Overall, he contributed to the knowledge of the electron.

Marie Curie

1898

Marie Curie was a scientist from Poland. She discovered polonium and was able to produce pure radium. She also organized a portable X-ray machine. She also created a theory of radioactivity and was able to isolate radioactive isotopes.

Pierre Curie

1903

Pierre Curie was a French scientist who created the Curie scale and more instruments to measure piezoelectricity. He is most well known for his studies on magnetism and temperature, as well as the Curie dissymetry principle. He also discovered nuclear energy.

Rutherford

1911

Rutherford was a scientist from New Zealand. He experimented to find atomic numbers. One of his experiments, which fired alpha particles into gas atoms, proved the existence of a dense nucleus inside atoms. He discovered alpha and beta rays, overturned Thomson's model, and proposed ideas about atomic structure. He won a Nobel Prize for these achievements.

Bohr

1912

Bohr was a scientist from Denmark. He applied the quantum concept to the problem of atomic and molecular structures. He observed that the Rutherford atomic model would be unbalanced and proposed that electrons could only occupy orbits determined by quantum of action. Electromagnetic radiation from an atom only occurs when an atom jumps to a lower orbit. Overall, he applied electrons to the periodic table and predicted more elements.

Schrodinger

1922

Schrodinger was an Austrian scientist. He experimented with electricity and radioactivity. He observed electrons in orbits of atoms and gave heights of distribution of radioactive substances. He worked on the creation of wave mechanics and a unified field theory. He also worked on how systems change with time.

Heisenberg

1925

Heisenberg was a German scientist. He had many theories about quantum mechanics and matrices. He is most well known for his uncertainty principle and his neutron-proton model of the nucleus. He later won a Nobel Prize for his accomplishments.

de Broglie

1929

De Broglie was a French scientist. He worked with quantum mechanics to produce ideas about wave mechanics. He united the physics of energy and matter and used this to predict the nature and movement of electrons. His accomplishments won him a Nobel Prize.

Chadwick

1932

Chadwick was an English scientist. He is well known for many reasons, including his artificial nuclear transformation experiment, his studies of the properties and structures of an atom, and his research on radioactivity. But he is most well known for his discovery of the neutron in an atom, for which he was able to win a Nobel Prize.

Irene Joliot-Curie

1935

Irene Joliot-Curie was a French scientist and daughter of the famous Marie Curie. Her work turned one element into another using radioactive isotopes. She also worked with nuclear fission. Her experiments identified a positron and neutron but failed to recognize it. However, it helped to develop later atomic theories. She later won a Nobel Prize for her efforts.

Lise Meitner

1938

Lise Meitner was a scientist from Austria. She discovered new isotopes, as well as nuclear fission, which is when the nucleus of an atom splits into smaller parts and releases energy. She also developed the idea of radioactive recoil, which is the movement of the nucleus during radioactive decay.

Rosalind Franklin

1951

Franklin was an English scientist. She used x-ray crystallography to capture an image of DNA, which later helped to develop the idea of the double-helix shape for DNA. Sadly, she is not credited for the discovery because others drew conclusions from the picture without her knowledge, and cut her out of the picture because she was a woman instead of a man.

Linus Pauling

1954

Linus Pauling was an American scientist. He worked with quantum mechanics to develop ideas about chemical compounds. He also contributed to the idea of a double-helix DNA. However, his most famous discovery was his work with chemical bonds and molecular orbits. He discovered ionic and covalent bonds and used these to create an atomic theory of a cluster of nucleons. His accomplishments won him a Nobel Prize.

Precision balance

1982

The precision balance was very important for chemistry. It allowed people to communicate their results with greater precision. It was created to measure mass, and over time it got more and more refined until it could measure past 0.0005g.