SCH4U REVIEW

Front

What are we talking about when we mention the development of a nuclear model of the atom?

Back

The process in which humans went from very little understanding of matter on an atomic scale to theorizing that atoms have a nucleus in the center and are surrounded by electrons.

Front

What did Democritus do?

Back

He was an ancient Greek philosopher around 400 BC who theorized that particles get to a size where they can no longer be divided. He called these particles "atomos" which means indivisible

Front

After Democritus, how long was the gap before Dalton came in.

Back

2,300 years later

Front

What did John Dalton do?

Back

He theorized around 1809 that atoms are small indestructible spheres. Atoms of the same element are identical

Front

What model did John Dalton come up with?

Back

The "billiard ball" model where an atom is a solid, uniform sphere

Front

What did JJ Thomson Do?

Back

Used the cathode ray tube experiment to discover the presence of electrons.

Front

What did Ernest Rutherford do?

Back

Created the gold foil experiment and discovered the nucleus

Front

What is the gold foil experiment?

Back

Positively charged alpha particles (type of radiation) were shot at a very thin sheet of gold foil. Most particles went straight through, but some particles were deflected and a few particles bounced back.

Front

What is the "nuclear model"?

Back

Atoms are mostly empty space with small, dense, positively charged "nucleus"

Front

Why does the atomic model not make sense?

Back

Nucleus composed of only positive charges should break apart due to repulsion forces. It also did not explain the total mass of an atom. Moving charges usually give off energy, thus the electrons should lose energy and crash into the nucleus but doesn't happen.