P1.1- particle model

Question 1

What was John Dalton’s model named as?

Answer 1

”Billiard Ball ( a “very small indestructible sphere” )

Question 2

What was J.J. Thompson’s model named as?

Answer 2

“Plum- Pudding Model”

Question 3

why did the particle model keep changing?

Answer 3

since new evidence can not be explained using old ideas

Question 4

What is the Rutherford model? (3)

Answer 4

+ positive nucleus (protons + neutrons)
+ negative electrons around
+ almost all mass of an atom is in the nucleus

Question 5

What is the Bohr model? (3)

Answer 5

+ electrons can only move in fixed orbits in shells around the nucleus
+ the model we use now
+ introduced shells

Question 6

How big is an atom’s diameter?

Answer 6

+ the diameter of an atom in 10^-10

10 to the power of minus ten

Question 7

Describe the structure of an atom

draw it out

Answer 7

+ a nucleus containing protons and neutrons

+ electrons moving around the nucleus

Question 8

Name Five features of Thompson’s model

Answer 8

+ positive mass
+ negative electrons embedded
+ was investigating rays given off by metals (cathode rays)
+ found out that an atom contained negative electrons
+ overall atoms are neutral (no charge)

+ MASS IS OVERALL DISTRIBUTED

Question 9

What was the main feature of Dalton’s model

Answer 9

all atoms in an element were the same

Question 10

What is a particle’s nucleus made of?

Answer 10

Protons and Neutrons

Question 11

How do electrons move around?

Answer 11

In fixed orbits

Question 12

What experiment did Rutherford do?

Answer 12

Fired alpha particles at a piece of gold foil
(alpha particles are positively charged)
- no need to mention they are positive

Question 13

What is the length of a molecule with 100 atoms?

Answer 13

10^-8m

Question 14

how and why has the model of the atom changed over time?

5 steps

Answer 14

• first model of the atom was a hard sphere.
• J. J. Thompson discovered that atoms contain smaller negatively charged electrons.
• model changed to a positive mass with electrons embedded in it
• Then Rutherford discovered that most of the mass was concentrated in a central nucleus.
• new model was a positively charged nucleus with electrons in orbit. - Bohr discovered that electrons could not be in any orbit.
• model changed to a positively charged nucleus with electrons in shells

Question 15

What is the name of Rutherford’s model?

Answer 15

Nuclear model