Atomic theory

Atomic theory

1. Is the idea that the matter is made up of little units called atoms

   • Ancient Greek beliefs
     • Leucippus and Democritus were the first to propose,in the fifth century B.C.That everything in made of tiny units called atoms
   • Dalton's theory
     • John Dalton an English chemist in 1808.He postulated that the matter is made of atoms.
     • Also he postulated taht all the atoms of the same element are identical,and are different from those make by different elements.
   • JJ.Thomson's theory
     • In 1904,the English physicist Joseph J.Thomson proposed the"plum pudding"theory of the divisible atoms
     • He discovered electrons in 1897
     • He postulated that the atoms are a big positively charged sphere with electrons.Positive charge equal to the negatives charge.
   • Rutherford 's theory
     • The British physicist Ernets Rutherford proposed a model of an atom with a nucleus on it in 1911
     • He postulated that the protons and electrons move in the central part and that neutral particles are in an atom.
   • Bohr's theory
     • He proposed a planetary model in 1913,in which the elctrons move arpud the sun similar to the pnaets orbit around the sun
     • The electrons have a "constant energy"
   • Schrodinger's theory(Quantum model)
     • He stated that electrons that electrons move in waves.They move in clouds where the position is uncertain
   • Chadwick's discover
     • He discovered the neutrons,which do not have any electrical charge,have a similar mass of a proton
   • Quark theory
     • The subatomic particles are divided in smaller particles called "quarks"

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