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442 BCE
Democritus
Ancient Greek (Born 460 BC) well known mostly for his formulation of an atomic theory of the universe. He observed the atomic theory by looking at an object being broken in half again and again until it could not be broken anymore. He called these atomos and figured out they make up everything. He said that the matter only consists of atoms and empty space. This is a very important discovery because it is the foundation of matter and elements. -
380 BCE
Aristotle
Aristotle was an ancient Greek philosopher and scientist born in 280 BC. He did not believe in the atomic theory. He believed that all substances were made up of fire, water, air, or Earth. He made many contributions in many fields of study. He also wrote the treatises. Many people believed his theory until it was proved wrong much later. -
770
Abu Musa Jabir ibn Hayyan
Jabir was a Muslim alchemist and many other things who preformed experiments during his time. He was the father of chemistry but people could not understand his work form other countries. He created a way to distill. He made a quantitative analysis of substances. He identified many new substances. He also laid groundwork for the periodic table. Most importantly to the atomic theory he created an idea of chemical bonds as a link between elements. Born in 721 and died in 815. -
1250
Albert Magnus
Saint Magnus was a German Catholic Dominican friar and bishop and philosopher. He discovered arsenic. He taught Christians about natural sciences. He was a famous teacher. -
1439
Printing Press (Gutenberg)
The invention of the printing press changed many things. Books could be made faster and cheaper causing them to be more accessible. People could then get books to read and become smarter. Ideas were also spread quicker. Communication was easier and this was one of the most innovative inventions ever. -
Robert Boyle
Robert Boyle was a man of Irish nationality. He was known for coming up with the element and Boyle's law, a relationship between the compression and expansion of a gas at a constant temperature. States that pressure of a gas varies inversely with its volume at a consistent temperature. The law was proposed in 1662. Boyle was a physicist. -
Vacuum tube and electric generator (Von Guricke)
He created the first electric generator in 1663. It produced static electricity. He studied the vacuum tube because he could see air combustion and respiration. These inventions helped discover more of what atoms were. -
Henry Cavendish
English philosopher and scientist. Discovered hydrogen gas and calculated density for hydrogen and other gases. (1731-1810) (He presented a paper on hydrogen or as he called it “inflammable air” in 1766) -
Precision Balance
First ever scale was recorded to be in 1770 and is credited to a man named Richard Salter. These first scales were springs scales where you would find the impact of the weight upon the spring to weight the item. Throughout the years numerous scales have come into productions from balance, mechanical, and digital. The measurements are never perfect and always contain an estimated final value.It could help measure or estimate the mass of an atom. -
Antoine Lavoisier
Lavoisier was a French chemist. He was central to the 18th century revolution of chemistry. He is considered the father of modern chemistry, established the law of conservation of mass in 1785. This means matter is conserved in a chemical reaction. -
John Dalton
(1766-1844) English Chemist, physicist, and meteorologist. Dalton is best known for proposing the modern atomic theory. This is important because it helped us figure put atoms and how they are made up. He said matter is made of all atoms, atoms are indescribable but cant be made, an elements atomic structure is unique, and rearranging atoms can cause chemical reactions.He observed these by doing experiments. Most of these were looked deeper into and scientist found out more. -
Amedeo Avogadro
Amedeo Avogadro- Italian chemist, (1777-1856)Best known for Avogadros law which states that under the same conditions of temperature and pressure, equal volumes of different gases contain an equal number of molecules. T The law is approximately valid for real gases at sufficiently low pressures and high temperatures. Did not discover avogadros number or the amount of units in one mole of a substance. (Avogadro's law was proposed in 1811, widely accepted 1858) -
Dmitri Mendeleev
Russian chemist and inventor, classification of elements, (1834-1937) Created the original periodic table of elements in 1869 (which was later expanded upon and improved upon by later scientists and their contributions). -
William Ramsay
Ramsay was a British chemist who discovered noble gases. He discovered four gases neon, argon, krypton, and xenon and explained that when they mixed with helium and radon formed new elements, the noble gases. -
Marie & Pierre Curie
French Scientists who were married, as such they get credit as a pair. They discovered plutonium and radium. They mainly studied radioactivity.
(plutonium was discovered in 1940) (Radium was discovered in 1898) -
JJ Thomson
Thomson was an English physicist. He was credited with the discovery and identification of the electron, and with the discovery of the first subatomic particle. He also came up with the "plum pudding" model of the atom. He lived from 1856-1940. Because of the importance to the atom the discovery of electrons was an important contribution as later chemists were better able to make the structure of the atom. -
Ernest Rutherford
Born in New Zealand of Scottish descent, professor of physics at Cambridge and the central figure in the study of radioactivity and the exploration of nuclear physics. (1871-1937). He preformed the gold foil experiment. He discovered alpha and beta rays and he discovered the nucleus from the experiment. He figured out that atoms also had empty space. These helped future chemists figure out the atom because he greatly helped. He found the nucleus was very small and dense. -
Niels Bohr
Bohr was from Denmark, 1885-1962. Bohr's greatest contribution to modern physics was the atomic model. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. It showed the electrons did not crash into the nucleus like previously thought. This led to Schrodinger work. -
Irene Joliot-Curie
French Scientist (1897-1956). Irene was the daughter of the chemists Marie and Pierre Curie. She expanded upon her parents studies doing important work on natural and artificial radioactive components, transmuting new elements, and nuclear physics. She discovered radioactive elements can be artificially made from stable elements. -
Louis de Brogile
Brogile was a French physicist who was known for his contributions the quantum theory. He discovered that matter has wave properties and came up with a theory of particle wave duality. He said particles and waves are similar and can preform the same function. -
Werner Heisenberg
Heisenberg was a German physicist who contributed to the atomic theory because of the quantum mechanics work he published in 1925. -
Erwin Schrodinger
Schrodinger was an Austrian Physicist. He took the Bohr model of an atom and used mathematical equations to figure out the chance of finding an electron in a certain way. He also came up with the wave equation for electron movements that changed quantum physics. He found the quantum mechanical model of an atom which means the 3 quantum numbers show the distributions of electrons in atoms. He showed electrons do not move around the nucleus. Its still today the widely accepted model of the atom. -
James Chadwick
Chadwick was an American physicist who discovered the neutron in atoms. It was discovered that Beryllium, when mixed with alpha particles made radiation. Chadwick then proposed that that was the neutrons and won the Nobel Peace prize for the discovery. This was a very important discovery for an atoms makeup. -
Lise Meinter
Meinter was Austrian-Swedish physicist who worked on radioactivity and nuclear physics. She helped discover nuclear fission. She also helped discover that the uranium atom, when mixed with neutrons splits. -
Rosalind Franklin
Franklin was a British biophysicist. She went to England in 1951 where she made important discoveries on how to make DNA specimens to get sharp x-ray patterns. Her work was used by Watson and Crick who are credited with making the model of the DNA structure. -
Linus Pauling
Pauling was an American chemist, biochemist, and peace activist. He researched the make up of the chemical bond and used it to clarify the structure of complex substances.