Chapter 1- Matter and Radiation

Question 1

What is the charge of the nucleus?

Answer 1

Positive

Question 2

What surrounds the nucleus of an atom?

Answer 2

Negatively charged particles called electrons

Question 3

What is the nucleus comprised of?

Answer 3

Positive protons and neutral neutrons that have approximately the same mass

Question 4

What can you infer about an uncharged atom ?

Answer 4

That it has equal amounts of protons and electrons.

Question 5

Why do radioactive substances emit radiation?

Answer 5

The nuclei of their atoms are unstable

Question 6

What can happen when radioactive substances pass through other substances?

Answer 6

It can ionise them.

Question 7

What are the three types of radiation from radioactive substances?

Answer 7

Alpha, beta and gamma

Question 8

Which radiation is the most ionising?

Answer 8

Alpha radiation

Question 9

Which radiation is the most penetrating?

Answer 9

Gamma

Question 10

What can stop alpha radiation?

Answer 10

A piece of paper

Question 11

What can stop beta radiation?

Answer 11

2-3mm of metal

Question 12

What is the half life of a substance?

Answer 12

The time it takes for the number of atoms of that substance to decrease by half.

Question 13

What is a nucleon?

Answer 13

A proton or neutron found in the nucleus.

Question 14

What do we know about atoms from Rutherford’s alpha scattering investigations?

Answer 14

Every atom contains:
A positively charged nucleus composed of protons and neutrons
Electrons that surround the nucleus

The nucleus contains most of the mass of the atom but occupies 0.000,01 times the diameter of the atom.

Question 15

What holds the electrons in the atom?

Answer 15

Electrostatic force between the negatively charged electrons and the positively charged nucleus.

Question 16

What do you notice about the mass of subatomic particles?

Answer 16

The electron has a much smaller mass than both the proton and the neutron.
The protons and neutron have almost equal mass.

Question 17

What do you notice about the charges of the subatomic particles?

Answer 17

The electron has equal and opposite charge to the proton. The neutron is uncharged.

Question 18

What is the same about all atoms of a given element?

Answer 18

They all have the same number of protons.

Question 19

What can be different about atoms of a given element?

Answer 19

They can have different numbers if neutrons.

Question 20

Define an isotope.

Answer 20

Atoms with the same number of protons but different numbers of neutrons.

Question 21

What is the nucleon number?

Answer 21

This is sometimes called the mass number.

The total number of protons and neutrons in an atom.

Question 22

What is a nuclide?

Answer 22

Each type of nucleus labelled using isotope notation.

Question 23

What is the specific charge of a charged particle?

Answer 23

It’s charge divided by its mass.

Question 24

What particle has the highest specific charge?

Answer 24

An electron.

Question 25

What part of the atom has zero charge?

Answer 25

A neutron.

Question 26

What part of the atom has the largest specific charge?

Answer 26

Electron

Question 27

What part of the atom leaves a different isotope of an element when it is removed.

Answer 27

A neutron

Question 28

What is the strong nuclear force?

Answer 28

The force that overcomes the electrostatic force of repulsion between the protons in the nucleus, keeping the protons and neutrons together.

Question 29

What is the range of the strong nuclear force?

Answer 29

No more than 3-4 centimetres

Question 30

At what distance does the attractive strong nuclear force stop?

Answer 30

At about 0.5fm. At separations smaller than this it is a repulsive force that acts to prevent neutrons and protons being pushed into each other.

Question 31

What can you note about the strong nuclear force between, two protons, two neutrons or one neutron and one proton?

Answer 31

The strong nuclear force has the same effect.

Question 32

Describe alpha radiation.

Answer 32

An unstable nucleus emits an alpha particle (2 protons and 2 neutrons) and forms a new nucleus. ``` Nucleon number (mass number) decreases by 4 Atomic number (proton number) decreases by 2 ```

Question 33

Describe beta radiation.

Answer 33

A neutron in the nucleus changes into a proton. A beta particle (an electron) is created and emitted instantly. An antineutrino is also emitted. Atomic number increases by 1. Nucleon number stays the same.

Question 34

Describe gamma radiation.

Answer 34

Electromagnetic radiation emitted by an unstable nucleus. | It has no mass or charge. It is emitted by a nucleus that has too much energy, post alpha or beta emission.

Question 35

How were antineutrinos detected?

Answer 35

They were detected as a result of their interaction with cadmium nuceli in a large tank of water.

Question 36

Which force (strong nuclear force or electrostatic force) does not affect a neutron?

Answer 36

Electrostatic force

Question 37

Which force (strong nuclear force or electrostatic force) has a limited range?

Answer 37

Strong nuclear force

Question 38

Which force (strong nuclear force or electrostatic force) hold the nucleons in a nucleus?

Answer 38

Strong nuclear force

Question 39

Which force (strong nuclear force or electrostatic force) tends to make a nucleus unstable?

Answer 39

Electrostatic force, repuslion between protons.