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460 BCE
Democritus
Democritus was a Greek scientist and philosopher who lived in Abdera, Greece. Democritus loved geometry and traveling. He was known as "The Laughing Philosopher." He presented a theory that particles are continuously moving and indestructible and made the main fundamental model of the molecule. His experiment consisted of him taking a seashell and breaking it in half over and over again until it couldn't be further divided. -
400 BCE
The Atom Was Discovered
Democritus proposed that atoms are the basic unit of matter, and cannot be further broken down (translates to"indivisible" in Greek). His experiment consisted of him taking a seashell and breaking it in half over and over again until it couldn't be further divided -
Antoine Lavoisier
Antoine-Laurent de Lavoisier was a French chemist and nobleman who studied in law school in his early years, while studying science on the side. Born August 26, 1743 || died May 8, 1794 in Paris, France. . -
John Dalton
John Dalton was born in Cumberland, England. Fun Fact: Dalton knew all gases might be liquefied provided their temperature was sufficiently low and pressure sufficiently high. When coming to atoms he believed every thing are made from atoms, atoms cannot be divided,and he contributed that each one atoms combine in unit to make compounds, atoms join together to form a replacement substance, and atoms have mass. -
"Law of Conservation of Mass" was established
Lavoisier was known for his experimentation aptitudes. One of his preferred tests being transforming HgO into Hg+O. He utilized this test to assist himself with establishment of the Law of Conservation. The law expresses that issue can't be made or demolished. He also indicates the modification of matter in responses. Matter reworked, yet never vanished."In a chemical reaction, mass is neither created nor destroyed." -
Dalton's Atomic Theory
Dalton believed atoms have mass and atoms of join together to form a replacement substance he knew this because he put 12 grams of carbon and 16 grams of oxygen which reacted with one another to form 32 grams of CO2 .The ratio of oxygen mass to CO2 mass was 2 to 1. Which proved atoms made from different elements had different masses. In 1808, he expressed newfound discoveries in his book, 'A New System of Chemical Philosophy'. -
Joseph John Thomson
Sir Joseph John Thomson, born (1856) in Manchester, UK, was a British physicist and Nobel Laureate in Physics. Thomson realized that the accepted model of an atom did not account for negatively or positively charged particles. He proposed the Thomson atomic model in 1904, that accounted for both protons and electrons. He used his research on cathode ray tube technology in this discovery. -
Max Planck
Max Karl Ernst Ludwig Planck was a theoretical physicist, born in Kiel, Schleswig (Germany) in 1858. He was known for originating the quantum theory: radiant energy is emitted or absorbed not continuously but discontinuously in the form of small packets of energy called quanta, and each wave packet (or quantum) is associated with definite amount of energy. This discovery won him the Nobel Prize for Physics in 1918. -
Marie Curie
Marie Skłodowska Curie, born in Warsaw, Poland (November 7, 1867), was a Polish physicist and chemist who conducted pioneering research on radioactivity. She discovered radioactive elements :radium and polonium(1897) along with her husband, Pierre Curie. She experimented by using a new method of chemical analysis, an electrometer to help with precise measurements when separating parts to see witch was most radioactive. -
Robert Millikan
Robert Millikan was a well known experimental physicist, born March 22, 1868, Morrison, IL.His contribution to the Atomic Theory was that atoms are composed of positive charges, and It determined the actual mass of the electron (which was proved in his oil drop experiment). He also discovered that matter can be conserved. In 1923, Millikan received a noble prize for his findings. -
Ernest Rutherford (1871-1937)
Born in New Zealand, 1871, Earnest Ruthford was a British physicist who came to be known as the "father of nuclear physics."
In 1911, Ernest Rutherford executed an exploration to test the plum pudding model. He terminated enthusiastic [He2+] elements at a foil and determined the diverting particles as they went ahead the opposite side. From this, he could conclude the data about the structure of the foil. Therefore, Rutherford discovered the nucleus.
