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400 BCE
Democritus
He was born in 460 BC and passed in 370 BC. He was a famous philosopher and was the first person to think up the idea of atoms. He concluded everything was made up of very small particles that were practically invisible. His entire idea was disregarded as Aristotle thought it to be complete nonsense. This was before they could test it so his contribution in 400 BC was forgotten until another scientist saw some potential in it. A fun fact is that he is called the Laughing Philosopher. -
Period: 400 BCE to
Atomic Theory Timeline
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John Dalton
He was born on September 5, 1766, and died on July 27, 1844. He is one of the most influential in this field. In 1808 he laid out the groundwork of what he believed atoms to be. He said all matter is composed of atoms and that all atoms are the same size. He said that atoms were the smallest particles and that they were tiny solid balls. He was also the first person to really start theorizing about the atom. He was never married and had no children. I thought that was very interesting. -
Sir Joseph John Thomson
He was born December 18, 1856 and died August 30, 1940. He also won the Nobel prize in 1906 and was knighted just like Chadwick. He had proposed one of the most important parts of an atom. He discovered the electron. He published his findings in 1897. After finding the electron, he proposed a model of the atom. While this isn't that similar to the others, but it is very important. -
Albert Einstein
Einstein was born March 14, 1879 and died on April 18, 1955.
His contribution to the atomic theory happened in 1905.
Albert Einstein mathematically proved the existence of atoms, and thus helped revolutionize all the sciences through the use of statistics and probability. Einstein was a part of the Manhattan Project furthering the production of atomic bombs. -
Robert Andrews Millikan
He was born March 22, 1868 and died December 19, 1953.
Like many on this timeline, Millikan won a Nobel Prize in 1923 for his study of the elementary electronic charge. He made his discovery in 1910. In 1910 Robert Millikan succeeded in precisely determining the magnitude of the electron’s charge. Millikan loved to play Tennis and Golf -
Ernest, Baron Rutherford of Nelson
Ernest was born on August 30, 1871 and died on October 19, 1937. His contribution to the atomic model was during 1911
The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun. He helped invent the now ubiquitous Geiger counter. -
Niels Henrik David Bohr
He was born October 7, 1885 and died November 18, 1962. He was one of the most influential scientists on this timeline. He contributed the most commonly referred model of an atom in 1913. This is what we think of when someone mentions an atom. Like most on this list, he won a Nobel prize for his contributions in 1922. A very interesting fact is that he was breaking ankles on the soccer field. He was reportedly a terrific soccer player. -
Prince Louis Victor Pierre Raymond de Broglie
Louis was born on August 15, 1892 and he died on March 19, 1987. He made his contribution in 1924. In 1924 Louis de Broglie introduced the idea that particles, such as electrons, could be described not only as particles but also as waves. This was substantiated by the way streams of electrons were reflected against crystals and spread through thin metal foils.
Louis was a Prince which is very cool. -
Erwin Rudolf Josef Alexander Schrödinger
Erwin was born on August 12, 1887 and died on January 4, 1961.
Erwin Schrödinger also won a Nobel prize the year after Heisenberg. He also is the man who came up with Schrödinger's cat. In layman's terms, the theory states that he will not know if the cat is dead or alive until he opens the box.
He made his discovery in 1926. His contributions were very important. He "formulated a wave equation that accurately calculated the energy levels of electrons in atoms." -
Werner Karl Heisenberg
Werner was born on December 5th, 1901, and perished February 1st, 1976. He is a renowned physicist that won the 1932 Nobel Prize for his hard work. He was a part of Germany's atomic program, which was in competition with The Manhattan Project. He made his contribution in 1927. Heisenberg's big contribution to Atomic Theory was his uncertainty principle. He also worked on the theory of the Atomic Nucleus. -
Sir James Chadwick
Chadwick was born on 20th October 1891 and sadly died on July 24, 1974. James made his contribution to the atomic model in 1932 James Chadwick's contribution to the atomic model was his discovery of the neutron. The neutron is a neutrally charged subatomic particle that is about the same mass as the proton. Both protons and neutrons occupy the nucleus of the atom. Chadwick was able to discover the neutron and measure its mass. As you can tell by his name he was knighted. That is a very fun fact.