Chemistry-History of the Atom

What is a scientific model used for?

Scientific model is used to explain experimental results

What can new experimental evidence lead to?

New experimental evidence can lead to a scientific model being changed or adapted

What was the first model of the element

John Dalton model of the atom

When was the John Dalton model of the atom though of

At the start of the 19th century

In the John Dalton model of the atom, what were atoms thought to be

Tiny spheres

What could the John Dalton model of the atom not do

Could not be divided

How were elements thought to be made in the John Dalton model of the atom

Different spheres made up different elements

What was the second model of the atom made

JJ.Thomson model of the atom or the plum pudding model of the atom

What did JJ Thomson discover

The Electron

What year did JJ Thomson discover the electron

1897

What did the discovery of the electron lead to

The plum pudding model of the atom

What did the plum pudding model suggest about the atom

The atom was a ball of positive charge with negative electrons embedded in it

What experiment was conducted that disproved the plum pudding model of the atom

The alpha particle scattering experiment

In what year did the alpha particle scattering experiment take place

1909

Who conducted the alpha particle scattering experiment

Rutherford and his student marsden

What was the alpha particle scattering experiment

Positive alpha particles were fired at a thin sheet of gold

What was expected to happen in the alpha particle scattering experiment

Due to the plum pudding model, they expected the alpha particle atoms to pass straight through because the positive charge of the atom was very spread out through the atom

What actually happened during the alpha particle scattering experiment

Most alpha particles went straight through as expected, However, some of the alpha particles were deflected back

How many alpha particles were deflected back

more then expected

What did the results of the alpha particle scattering lead to

The mass of the atom was concentrated in the nucleus. The nucleus was charged.

What was the third model of the atom

The Rutherford model of the atom

How was the Rutherford model of the atom made

The Rutherford model of the atom was made using the result of the alpha particle scattering experiment

What can the Rutherford of the atom also be called

nuclear atom

What was different about the Rutherford model of the atom

Positively charged nucleus where mass is concentrated. Surrounding this a cloud of negative electrons

what was the adapted version of the nuclear atom

Bohr model of the atom

What did bohr suggest about the atom

Electrons orbit the nucleus at specific distances

What did later experiments in the nucleus show

The nucleus could be subdivided into smaller particles. each particle having the same amount of positive charge

What were the positive particles in the atom called

protons

Whose work discovered the neutron

James chadwick

how long after the nucleus became excepted was the neutron discovered

20 years

where is the neutron found

in the neucleus