When was the first model of the atom created?
Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought. He proposed that matter could NOT be divided into smaller pieces forever. John Dalton created the very first atomic theory.
Democritus first suggested the existence of the atom but it took almost two millennia before the atom was placed on a solid foothold as a fundamental chemical object by John Dalton (1766-1844). Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought. 1) All matter is made of atoms.
- J. J. Thompson
- By 1920, physicists knew that most of the mass of the atom was located in a nucleus at its center, and that this central core contained protons. In May 1932 James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron.
A bust of Democritus (or Democrites), who came up with the idea of indivisible atoms. The earliest known proponent of anything resembling modern atomic theory was the ancient Greek thinker Democritus. He proposed the existence of indivisible atoms as a response to the arguments of Parmenides, and the paradoxes of Zeno.
- According to Dalton's Atomic Theory, Atoms of one element cannot be changed into atoms of a different element by chemical reactions and atoms can neither be created nor destroyed in chemical reactions.
- Questions and Answers
Element Name Discovered By Year Aluminum Hans Christian Oersted 1825 Americium Glenn T. Seaborg Ralph A. James Leon O. Morgan Albert Ghiorso 1944 Antimony Known since ancient times ? Argon Sir William Ramsay Lord Rayleigh 1894
- John Dalton
- A necessary prerequisite to the construction of the periodic table was the discovery of the individual elements. Although elements such as gold, silver, tin, copper, lead and mercury have been known since antiquity, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous.
- Dimitri Mendeleev
- The periodic table was arranged by atomic mass, and this nearly always gives the same order as the atomic number. However, there were some exceptions (like iodine and tellurium, see above), which didn't work. Mendeleev had seen that they needed to be swapped around, but it was Moseley that finally determined why.
Updated: 3rd October 2019