Chapter 1. Worksheet #1a

Question 1

In Ancient Greece, Democritus and Aristotle did not have any equipment, and had to base their ideas off of what?

Answer 1

Reasoning

Question 2

What did Democritus believe about the model of matter? (2).

Answer 2

1. All matter consists of identical, indestructible particles called atoms
2. Atoms are indivisible and cannot be divided further

Question 3

What did Aristotle believe about the model of matter? (2).

Answer 3

1. All matter consists of different combinations of earth, air, fire, and water
2. Matter can be infinitely divided

Question 4

Did Aristotle agree with Democritus’ ideas of the atom?

Answer 4

No, he rejected them

Question 5

What were Dalton’s ideas on the model of the atom? (5).

Answer 5

1. All matter is composed of tiny indestructible, indivisible particles called atoms
2. Atoms of the same element are identical
3. Atoms of one element are different from those of another element
4. Atoms of different elements combine to form compounds in a fixed whole number ratio
5. Atoms are never created or destroyed in chemical reactions

Question 6

What is Thompson’s model of the atom?

Answer 6

The negatively charged electrons were embedded in a positively charged sphere

Question 7

What did Thompson discover?

Answer 7

Electrons

Question 8

What device lead Thompson to discovering the electron?

Answer 8

Cathode ray

Question 9

During Thompson’s experiment, the observation that a glowing ray appeared in the tube regardless of the metal used lead him to the conclusion that…

Answer 9

The ray must be common to all elements

Question 10

During Thompson’s experiment, the observation that the ray made a pinwheel spin lead him to the conclusion that…

Answer 10

The ray must be made of some type of particle

Question 11

What observation lead Thompson to discover the electron?

Answer 11

The ray was attracted to the positive end of a magnet, and was repelled from the negative end

Question 12

During Rutherford’s experiment, he observed that most of the alpha particles passed through the gold foil, which lead him to the conclusion that…

Answer 12

The atom must be made of mostly empty space

Question 13

During Rutherford’s experiment, he observed that some of the alpha particles are slightly deflected off course, which lead him to the conclusion that…

Answer 13

Some of the alpha particles slightly touched the nucleus of the atom

Question 14

During Rutherford’s experiment, he observed that a very small number of the alpha particles bounced backwards, which lead him to the conclusion that…

Answer 14

They (positive alpha particles) hit the nucleus (positive charge) and repelled from it

Question 15

Therefore, what did Rutherford discover?

Answer 15

At the center of the atom is a nucleus consisting of positively-charged protons. Negatively-charged electrons orbit the nucleus

Question 16

How come electrons don’t get pulled into the nucleus? (Rutherford-Bohr model)

Answer 16

Electrons travel around the nucleus in specific orders

Question 17

How do electrons change orbits and what happens?

Answer 17

• Electrons change orbits when they lose or gain energy
• Gain energy=> farther orbit
• Lose energy=> closer orbit

Question 18

What else happens when electrons lose energy?

Answer 18

They emit energy in the form of light

Question 19

What did Chadwick discover?

Answer 19

Neutrons