The Atomic Theory is a theory that explains what matter is made of. The Atomic theory states that matter can’t be divided as it is made up of minute particles called atoms that cannot be separated. The very word atom is derived from the Greek word Atmos which means indivisible.
Atomic theory timeline-
Year Person/People Event
442 BCE Democritrus and Leucippus These Greek philosophers came up with the idea that all matter is composed of indivisible elements.
1803 John Dalton British chemist and physicist John Dalton theorised that matter is composed of spherical atoms (that are in motion) of different weights and are combined in ratios by weight.
1896 Wilhelm Rontgen Discovered that certain chemicals glowed when exposed to cathode rays. These chemicals were special because they weren’t deflected by the magnetic field produced in the cathode ray tube (which was built by Sir William Crookes in 1870).
He Called these X-rays.
1896 Henri Becquerel Accidentally discovered spontaneous radioactivity.
1898 Pierre and Marie Curie Pierre and Marie hypothesised that radioactive particles cause atoms to break down, then release radiation that forms energy and subatomic particles.
1898 JJ Thomas Discovered the electron, using properties of cathode rays.
1900 Max Planck Introduced the quantum theory- stating that electromagnetic energy could only be released in quantized form.
His ‘quanta’ are now referred to by physicists as ‘photons.’
1905 Albert Einstein Created special and general theories of relativity and speculated upon the particle nature of light. This was the basis of understanding nuclear energy.
1908 Robert Millikan Measured the charge of an electron. The charge of one electron is known as the elementary charge.
1909 -- Ernest ...
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...ces are secondary sources, I had to be very careful that the websites that I chose contained reliable information and diagrams. I believe that I have been very careful with my sources and have chosen ones that are both accurate and informative and have helped me to develop my ideas about Marie Curie and the atomic theory in many ways.
http://www.softschools.com/timelines/atomic_theory_timeline/95/ http://www.nobelprize.org/nobel_prizes/themes/physics/curie/ http://www.buzzle.com/articles/accomplishments-of-marie-curie.html http://www.aip.org/history/exhibits/curie/resbr2.htm http://www.earthmagazine.org/article/benchmarks-henri-becquerel-discovers-radioactivity-february-26-1896 http://www.aps.org/publications/apsnews/200412/history.cfm http://www.nist.gov/pml/general/curie/1927.cfm