The Development of Atomic Theory

Who thought that atoms were tiny, solid spheres with no smaller particles within them. and also predicted that atoms could not be destroyed?

• Democritus

• Aristotle

• Plato

• Thomson

Who proposed atomic theory in 1808?

• Democritus

• Jon Dalton

• Ernest Rutherford

• J J Thomson

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NGSS.HS-PS1-7

In 1808, John Dalton proposed his atomic theory. Recall which of the following statements is one of the main ideas of Dalton's atomic theory.

• Atoms are solid spheres

• All matter is composed of indivisible atoms

• Atoms are made up of smaller charged particles

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NGSS.HS-PS1-7

Who proposed a model of the atom that is now called the plum pudding model?

• J J Thomson

• Ernest Rutherford

• James Chadwick

• John Dalton

Rutherford carried out an experiment where he fired a stream of alpha particles at a very thin sheet of gold foil. He found that most of the alpha particles passed straight through the foil, while some were deflected at a small angle and some were deflected directly back.

Rutherford carried out an experiment where he fired a stream of alpha particles at a very thin sheet of gold foil. He found that most of the alpha particles passed straight through the foil, while some were deflected at a small angle and some were deflected directly back.

Specify what this experiment told Rutherford about the structure of the atom.

• Atoms are indivisible solid spheres

• All atter is made up of atoms

• Electrons are scattered through a positive shpere

• Atoms have a small, dense and posititvely charged nucleus at the centre.

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NGSS.HS-PS1-8

The main ideas of Dalton's theory were:

1. All matter is composed of ------------ atoms.

2. All the atoms of a given element are ---------.

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NGSS.MS-PS1-1

Name the first person to propose the idea of atoms.

• Socrates

• Plato

• Democritus

• Aristotle

Specify which of these is one of the main ideas behind Democritus' model of the atom.

• Atoms are tiny

• Atoms are composed of subatomic particles

• Negatively charged particles exist within atoms

• Atoms are mostley empty spaces

Democritus proposed his idea of atoms around 460 BC

. what was the main reason why his idea of atoms was dismissed when he proposed it?

• Atoms are very tiny to be seen so that there was no evidence they existed.

• The Greeks were preoccupied with fighting to pay attention to Democritus

• Democritus did not publish his findings in an official scientific textbook.

Who carried out a cathode ray experimentand discovered Electrons in 1897?

• J. J. Thomson

• Ernest Rutherford

• John Dalton

• Chadwick