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410 BCE
Democritus
Democritus' theory involved using his own reasoning. He based his work off of other philosophers of his age and was the first person to say that materials were made up of smaller particles which he called 'atomos'. Democritus also thought that no matter how small you cut an object up, it would always keep the same properties as the object in its full state. -
350 BCE
Aristotle
Aristotle (a philosopher) thought that Democritus' theory was incorrect. He believed that everything was made through four elements, which were earth, fire, water, and air. His theory was that "a mass of incomprehensible size was everywhere" (which he called hyle). Also he said that material is always just one"thing", instead of being made of multiple particles. -
1530
George Bauer
By some, George Bauer was considered a "founder of geology" and contributed to the further study of minerals, fossils, and rocks in geology. He's most known for his book "De Re Metallica", which talks about what George knew about mining, its machinery, how to find certain ores, and more. He learned most of his knowledge in the late 1520's to the early 1530's. -
Robert Boyle
Robert was one who experimented with many types of gases. He taught about atoms possibly existing, made the distinction between mixtures and compounds, and found out how to turn regular metals into gold. He proposed the theory that elements are composed of "corpuscles" of different types/sizes that could organize themselves into groups that represent dissimilar substances. There was also had Boyle's Law, which expressed the relationship between the pressure and a gas' volume. -
Antoine Lavoisier
Antoine was known for doing many experiments and was the person that composed the "Law Of Conservation Of Mass." This stated that matter couldn't be created or destroyed, just like how energy can't be created or destroyed. He also said that matter can be rearranged, but cannot just disappear. -
Joseph Proust
Joseph Proust's main contribution was that he made the Law of Definite Proportions, which states that "the ratio of elements in a compound is always constant." Joseph had to defend his law when another chemist (Claude Berthollet) tried to refute it, but Joseph defended it successfully. Another notable thing he did was suggesting that matter could be put together to make something much bigger. -
John Dalton
John did lots of research in libraries over people in history who thought of ideas surrounding the atom. He is most commonly known for "Dalton's Theory," which contains 6 parts to it. They are: matter is composed of extremely small particles (atoms), atoms are indivisible/indestructible, atoms of a given element are identical, atoms of specific elements are different than those of other elements, and in chemical reactions, atoms separate, combine and/or rearrange. -
Joseph-Gay Lussac
Joseph was mostly known for the two laws that he came up with in the 1800's. Out of the two, Gay-Lussac’s law is the more prominently known one, which stated that "gases at constant temperature and pressure combine in simple numerical proportions by volume, and the resulting product or products also bear a simple proportion by volume to the volumes of the reactants." -
Amedeo Avogadro
Amedeo is most commonly known for the hypothesis he had (which eventually turned into "Amedeo Avogadro's Law"), which stated that when all gases have an equal volume and are at the same temperature and pressure, then they have the same number of molecules. He backed up his law with many experiments to prove his hypothesis, even though it wasn't believed at first. His work is related as well to the work of Joseph-Gay Lussac and John Dalton. -
J.J. Thomson
J.J. was known for creating the "cathode ray." When a high voltage current is sent through this tube, it and the atoms hit the outside of the tube glows. This invention (with many different parts) enabled him to make many experiments in which he could test out things like polarity of atoms. He was also known for his comparison of plum pudding to an atom and made the "Plum-Pudding Model." -
Henri Becquerel
Henri was considered by many to be main person who discovered radioactivity (father of radioactivity). He did many experiments with radioactivity, using X-rays and uranium salts, in which he found out much about how radioactivity works and what it is. The unit of radioactivity, the becquerel (Bq), is also named after his last name. Finally, Henri won the Nobel Prize in 1903 for his finds in radioactivity. -
Max Planck
Max was a physicist who's biggest accomplishment was developing the Quantum Theory, which is the "theoretical basis of modern physics that explains the nature and behavior of matter and energy on the atomic and subatomic level." It deals with quantum mechanics, which that deals with electrons, photons, and other particles in the universe that are particularly small. -
Ernest Rutherford
Ernest was considered "a pioneer of nuclear physics" and he was the first person to split the atom. He did many experiments, with his most famous one being the gold-foil experiment, which helped in the discovery in the nucleus and helped make a model of an atom called the "Rutherford Model." So to sum it up, he kickstarted the understanding of the interior of an atom. He also won the 1908 Nobel Prize in Chemistry for his advancements in chemistry and knowledge of the atom. -
Niels Bohr
Niels was mostly known for his study on the structure of the atom. While the "Bohr Model" (which he made) was pretty accurate, future chemists did fix up the problems. This was a model in which "the negatively-charged electrons orbit a small, positively-charged nucleus." This motion is like how the plants in our solar system orbit the sun. His model (and a few lesser achievements) is what led him to win the 1922 Nobel Prize in Physics. -
Robert Millikan
Through an oil-drop experiment, Robert was the one to discover the underlying charges of an electron. Other things he was notable for was trying to verify Einstein's theories and equations through experiments, and winning the "Nobel Prize in Physics" in 1923 for "his work on the elementary charge of electricity and on the photoelectric effect (one of Einstein's equations)." -
Louis de Brogile
Louis is most commonly known for his research into the quantum theory and for finding a way to predict the wave nature of electrons (in the way that electrons move around the nucleus in one restricted way). His ideas of "matter waves" wasn't popular at first, but once his thesis was sent to Einstein, he was amazed and said about Louis' work is helping. He also won the the Nobel Prize for Physics in 1952. -
Werner Heisenberg
Werner is one of the pioneers of quantum mechanics, along with other people in this timeline. The thing though that he is most known for is his "uncertainty principle", which talked about about how we will never know the exact place where something is or exactly how fast something is moving. He was also awarded the Nobel Prize for Physics in 1932. -
Erwin Schrodinger
Erwin was known because of him making his own model (based off of Bohr's Model) called the "Schrodinger Model", contributing to the wave theory (by Louis de Broglie), and making the "Schrodinger Equation" (1926), which is used to find the allowed energy levels in quantum mechanic-related tools. He also won the Nobel Prize in 1933, like most of the others in this timeline.
