-
340
Aristotle
Aristotle didn't think atoms could be constantly moving if they were in a void. People thought Aristotle's opinions were very important, because of his disbelif of Democritus's atomic theory many others didn't berlieve it. -
460
Democritus
Many belived if you cut a substance multiple times you would eventually creat an uncuttable piece. Democrtus called these particle pieces atomos, which means not to be cut . He belive the particles moved and combined together. His ideas had no effect on later Greek philosiphers. -
Period: 460 to
Atoms
No work was done on atoms during this time -
John Dalton
His atomic therory stated that all matter is made of atoms. Atoms are indivisible and indestructible. All atoms of a given element are identical in mass and properties. A chemical reaction is a rearrangement of atoms. Atoms can be neither created nor destroyed. -
Joseph John Thomson
Thomson descovered the electron and changed the view of an atom.Thomson's atomic theory proposed a model of atom which is known as plum pudding model. He theorory sugesrt that, althought an atom was unbreakable, an atom was made up of electrons and protons. He said that atoms are electrically neutral because the positive and negative charges are equal in magnitude. -
Ernest Rutherford's Expirament
Ernest Rutherford conducted an experiment with two other scientists.They studied the deflection angles of "alpha particles" that they shot through a thin layer of gold. Alpha particles are just helium atoms stripped of their 2 electrons. In 1920 he also predicted the existence of the neutron. -
Ernest Rutherford
Ernest Rutherford was a New Zealand physicist who explained natural radioactivity, determined the structure of the atom, and changed one element into another (nitrogen to oxygen) by splitting an atom's nucleus. Rutherford's description of an atomic structure with orbital electrons became the accepted model -
Niel's Bohr
He proposed that electrons:
orbit the nucleus without losing energy;
could move only in fixed orbits of specific energies.
Electrons with low energy would orbit closer to the nucleus while electrons with high energy orbit further from the nucleus. -
Louis de Broglie
In 1924, a French physicist named Louis de Broglie suggested that, like light, electrons could act as both particles and waves -
James Chadwick
In 1932 James Chadwick identified the neutron. -
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Conclusion
So in conclusion many scientist helped to uncover the atom. Although scientist today still have questions.
