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470
Democritus
*460 BC-370 BC
Democritus and Leucippus, his mentor, invented the atomic theory, which states that:
-everything is composed of atoms which are physically, but not geometrically, indivisible
-between atoms is empty space
-atoms are indestructible
-they have always been, and always will be, in motion
-there are an infinite number of atoms, and kinds of atoms
He is considered by many as the Father of Modern Science. Wikipedia: Democritus -
500
Medieval Alchemy
500-1500
Alchemy was the "science" of looking for wealth and eternal life. Despite never finding the philosopher's stone, alchemists came up with the basic concept of the atom. Although this wasn't an official discovery, alchemy is credited with improving our atomic knowledge. Unfortunately, most alchemists died at an early age because they experimented with toxic metals like lead and cadmium.
Wikipedia: Alchemy -
John Dalton
1766 - 1844
Dalton wrote the atomic theory which states that:
-Elements are made of tiny particles called atoms
-The atoms of a given element are different from those of any other element
-All atoms of an element are identical
-Atoms can form chemical compounds
-Atoms cannot be created, divided, or destroyed Dalton's prolific collection of works later influenced many famous scientists, such as James
Chadwick and Niels Bohr. Wikipedia -
Henri Becquerel
1852-1908
Henri Becquerel came from a family that produced four generations of renowned scientists. He won the 1903 Nobel Prize for Physics along with Marie and Pierre Curie for the discovery of natural radioactivity.His research inspired many scientists to further study radioactive atomic structure.The SI unit for radioactivity (Bq) is named in his honor. Wikipedia: Bequerel -
J.J. Thomson
1856-1940
Thomson discovered the electron in 1877 through his study on the quality of cathode rays, which are basically rays of electrons in a vacuum. He estimated the electron's weight to be approximately a thousandth of the weight of an atom.He was the first one to suggest the existence of subatomic particles; never before had anyone imagined there would be something smaller than an atom. Wikipedia: J.J Thomson -
Ernest Rutherford
1871-1937
Known as "The Father of Nuclear Science", Rutherford was the first person to hypothesize the existence of a nucleus, a dense core in the center of an atom. He eventually discovered the proton. He is credited with being the first one to succesfully split the atom in 1917. He also came up with the terms "alpha" and "beta" to differentiate the two types of radiation emitted by thorium.
Wikipedia: Rutherford -
Niels Bohr
1885-1962
One of the most important scientist of his time, Bohr won the Nobel Prize in Physics for his contributions to quantum physics and the atomic structure. He invented the Bohr model, which depicts the atom and the electron orbits accurately. It is still commonly used to represent atomic structure. One of his sons, Aage Bohr, ended up winning the Nobel Prize for Physics as well. Wikipedia: Niels Bohr -
James Chadwick
1891-1974 James Chadwick was awarded the Nobel Prize for Physics for the discovery of the neutron.His work led the way to man-made elements. He was also involved in the study of nuclear fission, which was a groundbreaking discovery at the time. He also was a part of the Manhattan project, and contributed the the development of the atomic bombs dropped in Hiroshima in World War II. Wikipedia: James Chadwick -
Marie & Pierre Curie
Marie1867-1934
Pierre1859-1906
Marie and Pierre Curie discovered radioactivity together. In the process, they succeeded in isolating two new elements, polonium (named after Marie's home country) and radium. Having discovered radioactive atoms, Marie died premature due to overexposure to radioactivity. Her papers and belongings are now considered too dangerous to handle, and are contained in lead casings for safety. Wikipedia: Marie Curie
