Chapter 12 - Atomic Structure

Question 1

What did Rutherford do and notice which led to the gold foil experiment?

Answer 1

He noticed most alpha particles passed straight through a thin mica sheet, suggesting that there was a large amount of empty space in the atom.

Question 2

Define nuclear model of the atom?

Answer 2

A model of the atom in which negative charges (electrons) are distributed outside a tiny nucleus of positive charge.

Question 3

Explain the gold foil experiment?

Answer 3

Box containing a vacuum. Thin sheet (few hundred atoms) of gold feel placed in between alpha source and detector. Detector is made of a scintillating material which flashes each time it’s struck by alpha, microscope used to see flashes. Alpha source turned on, flashes counted, when one doesn’t reach they know it must have been deflected by nucleus.

Question 4

Rough radii of proton, neutron, nucleus, atom?

Answer 4

Proton/neutron 10^-15m
Nucleus 10^-15/-14m
Atom 10^-10m

Question 5

Size of femtometre ?

Answer 5

10^-15m

Question 6

Define nucleon?

Answer 6

A particle found in an atomic nucleus.

Question 7

Define nucleon number?

Answer 7

The number of neutrons and protons in the nucleus of an atom.

Question 8

Define neutron number?

Answer 8

The number of neutrons in the nucleus of an atom.

Question 9

Define proton number?

Answer 9

The number of protons in the nucleus of an atom.

Question 10

What is the relative atomic mass and charge of an alpha particle?

Answer 10

+2e

4

Question 11

Define nuclide?

Answer 11

A specific combination of protons and neutrons in a nucleus.

Question 12

What happens to the ratio of neutrons to protons as an atom gets heavier?

Answer 12

Ratio gets larger (more neutrons than protons).

Question 13

Define isotope?

Answer 13

Nuclei of the same element with a different number of neutrons but the same number of protons.

Question 14

Define ion?

Answer 14

An atom with a net positive or negative charge.

Question 15

Define strong nuclear force?

Answer 15

A fundamental attractive force of nature that acts between quarks.

Question 16

What does the strong nuclear force do?

Answer 16

It holds the nucleus together.

Question 17

Why is the strong nuclear force required?

Answer 17

Because the electrostatic repulsive force is much much larger than the gravitational force between protons therefore another force is required to hold the nucleus together.

Question 18

Why are there more neutrons than protons in heavier nuclei?

Answer 18

Because the strong nuclear force is very short ranged but the electrostatic repulsive force is long-ranged. Therefore in heavier nuclei there are more neutrons to dilute the protons.

Question 19

Define hadrons?

Answer 19

Particles consisting of quarks such as the proton or the neutron.

Question 20

Define leptons?

Answer 20

A group of fundamental particles that includes the electron and the neutrino.

Question 21

Define quarks?

Answer 21

Fundamental particles that make up hadrons, such as the proton and neutron.

Question 22

Name a difference between hadrons and leptons?

Answer 22

Hadrons are affected by the strong nuclear force but leptons are not.

Question 23

What are the six types of quarks?

Answer 23

Up quark down quark strange quark and their antiquarks

Question 24

What quarks make up a proton?

Answer 24

u u d

Question 25

What quarks make up a neutron?

Answer 25

u d d

Question 26

What quarks make up a phi meson?

Answer 26

Strange quark and an anti-strange quark.

Question 27

What does the line above a quark mean?

Answer 27

It means it is an antiquark

Question 28

What three factors do you quarks account for?

Answer 28

Charge (Q)
Baryon number (B)
Strangeness (S)

Question 29

What is the quark table?

Answer 29

Notes

Question 30

Define plum pudding model?

Answer 30

A model of the atom in which negative charges are distributed throughout a sphere of positive charge.

Question 31

Pi+ meson make up?

Answer 31

u and anti d

Question 32

Phi meson make up?

Answer 32

s and anti s