Atoms

Question 1

Why has no one ever seen an atom?

Answer 1

Because an atom is too small and moves too rapidly to be seen

Question 2

Although atoms cannot be seen, how has man gained information about them?

Answer 2

1. Spectroscopes
2. Field-emission microscopes
3. Photographic film
4. Geiger counters

Question 3

What is the purpose of an atomic model?

Answer 3

To summarize all the known facts about atoms in order to explain their behaviour

Question 4

Who designed the first atomic model and when?

Answer 4

John Dalton - 1808

Question 5

What charge does this symbol represent? +

Answer 5

Positive

Question 6

What charge does this symbol represent? -

Answer 6

Negative charge

Question 7

If two substances attract each other, what does this mean?

Answer 7

This means one has a negative charge while the other has a positive charge. Opposites attract.

Question 8

If two substances repel each other, what does this mean?

Answer 8

This means the two substances have the same charge, either positive or negative. Same charges repel

Question 9

In an atom, what do you call a positive charge?

Answer 9

A proton

Question 10

In an atom, what do you call the negative charge?

Answer 10

An electron

Question 11

What are the five atomic models?

Answer 11

1. Dalton model
2. Thomas “plum pudding” model
3. Rutherford “planetary” model
4. Bohr “orbital” model
5. “Wave-mechanical” model (electron cloud)

Question 12

What is the best atomic model for a physicist?

Answer 12

The wave-mechanical model

Question 13

What is the best atomic model for a chemist?

Answer 13

The Bohr “oribital” model

Question 14

What orbits around the nucleus of an atom? What else do they whilst orbit?

Answer 14

Electrons. They also rotate

Question 15

What does the rotating of electrons whilst orbiting the nucleus cause?

Answer 15

Magentism

Question 16

The atom’s nucleus contains both what?

Answer 16

Protons and electrons

Question 17

Why does a neutral atom need to contain an equal number of protons and electrons?

Answer 17

Because they have opposite electrical charges. This balances it.

Question 18

What takes up most of an atom’s volume?

Answer 18

The orbits of the electrons

Question 19

Where are most of an atom’s mass contained?

Answer 19

In its nucleus

Question 20

Why was the neutron discovered much later than the other parts of the atom?

Answer 20

Because a neutron:
1. Carries no charge
2. Usually, it has no effect on other objects

Question 21

What does the neutron do?

Answer 21

It overcomes the repulsive force of the positive protons and binds the
protone and neutrons together in the nucleus

Question 22

What determines the isotope an atom exists in?

Answer 22

The number of neutrons in the nucleus of the atom.

Question 23

What deteremines magnetism?

Answer 23

The direction of the rotation of electrons that revolve around the nucleus