Atom

Alike

All atoms of the same elements are _____.

Atoms

All element are composed of _____.

Different

Atoms of different elements are ______.

Compound

Atoms of different elements combine to form a ______.

Lord Ernest Rutherford

Conducted a famous experiment called the gold foil experiment. He used a thin sheet of gold foil and special equipment to shoot positively charged alpha paricles at the gold foil. Most particles passed straight through the foil like the foil was not there. Some particles went straight back or were deflected as if they had hit something.

Niels Bohr

Danish physicist. Proposed a model of the atom that is similar to the model of the solar system. The electrons go around the nucleus like planets orbit around the sun. All electrons have their energy levels - a certain distance from the nucleus. When electrons release (lose) energy they go down a level. When electrons absorb (gain) energy they go to a higher level.

John Dalton

English chemist. Ideas formed the atomic theory of matter.

J.J Thompson

English scientist. Discovered the electron when he was experimenting with gas discharge tubes. He noticed a movement in a tube. He called the movement cathode rays. The rays moved from the negative end of the tube to the positive end. He realized thay the rays were made of negatively charged particles called electrons.

Release energy

For an electrons to fall from the third energy level to the second energy level, it must _________ energy.

The electrons moved around the nucleus like plants orbit the sun.

How could Bohr's model be called a planetary model of the atom?

The particles went straight through the nucleus

How did Rutherford know that an atom was mostly empty space?

They repelled the positively charged particles - alike charges repel

How did Rutherford know that the nucleus was positively charged?

They have their own energy levels - distance from the nucleus

How do electrons in the same atom differ?

32 electrons

How many electrons are in the fourth energy level?

Electrons

What are cathode rays made of?

Atoms

What are elements made up of?

The electron and its charge

What did J.J Thompson discover?

As they hit the gold foil, the alpha particles passed straight through or were deflected

What happened to the alpha particles as they hit the gold foil?

Positively charged particle

What is the charge of an alpha particle?

Negatively charged

What is the charge of an electron?

Atomic Theory of Matter

What is the name of John Dalton's theory?

Thompson was working with gas discharge tubes.

What was Thompson working with when he discovered the cathode rays?

Because they are negatively charge and attracted to the positive end

Why do electrons move from the negative end of the tube to the positive end?

Absorb energy

Would an electron have to absorb or release energy to jump from the second energy level to the third energy level?