Atomic+Theory+Totem+Poles

__Dalton __ (1803) - John Dalton was an english chemistry teacher who first studied how elements combine to form new compounds! He postulated that elements were made of tiny, indivisible spherical particles called atoms! He modeled the word atoms off of Democritus' original term for these particles, __** atomos **__ (indivisible in greek).

Astor's Atomic Model Drawing for Dalton:

Astor's Totem Pole Model for Dalton

__Thomson __ (1897) J.J. Thomson, a British scientist, used a __** cathode ray tube **__ and big magnets to detect the first subatomic particle. His results proved that the subatomic particle he found was 2000x lighter than the hydrogen atom and that these were negatively charged. He called these particles __** electrons **__.

The discovery of subatomic particles meant that Dalton's indivisible sphere idea was not correct! Thomson decided to call his new model for the atom, __** The Plum Pudding Model **__.



Astor's Atomic Model Drawing for Thomson:

Astor's Totem Pole Model for Thomson:

__Rutherford __ (1911) Lord Ernest Rutherford was a New Zealand chemist who performed the gold foil experiment where he shot positively charged alpha particles at a thin sheet of gold foil. His data showed that >98% of alpha particles went //**straight through**// the foil unchanged. This must indicate that most of the atom is filled with **//nothingness//**!

Almost 2% of the particles were deflected at slight angles, and about 0.01% hit the foil, and then bounced straight back. Wow!

Rutherford said that there must be something very tiny and positively charged in the atom, and he dubbed this, the __** nucleus **__! This discovery identified that the atom was not a gloppy positive fluid filled with negative electrons as Thomson had said, and Lord Rutherford called his new model __** The Nuclear Model **__!



Astor's Atomic Model Drawing for Rutherford:

Astor's Totem Pole Model for Rutherford:

__Bohr __ (1913) A Danish scientist named Neils Bohr is famous for discovering that when gaseous atoms are zapped with electricity, they give off light in certain colors. When he realized that specific atoms give off only a few colors, he postulated that the excited electrons that give off the colored light must orbit around the nucleus at certain distances. We only see light when electrons jump from one orbit to another one, //meaning they're not free to roam everywhere as Rutherford had said!// Bohr's atomic model was eventually called the Solar System Model, but is generally referred to as __** The Bohr Model **__.

Astor's Atomic Model Drawing for Bohr:

Astor's Totem Pole Model for Bohr's Model for an ion of Nitrogen that has satisfied the Octet Rule:

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