Unit 4 - Lesson 11: Radioactivity

Question 1

What are atoms made of?

Answer 1

A central nucleus of protons and neutrons. They can also be called nucleons.

Question 2

What floats around the nucleus in areas called shells (sometimes called clouds)?

Answer 2

Electrons.

Question 3

How much smaller are the electrons than the protons and neutrons?

Answer 3

The electrons are 2000x smaller than the protons and neutrons. They have a very small mass.

Question 4

There are different types of atom, each with a unique number of protons, neutrons and electrons. What are they called?

Answer 4

They’re called elements.

Question 5

Elements are given what to show their unique number of protons, neutrons and electrons?

Answer 5

Each element is given a mass number and atomic number.

Question 6

What is the mass number?

Answer 6

The mass number = the number of protons + the number of neutrons

Question 7

What is the algebraic symbol for mass number?

Answer 7

A

Question 8

What is the atomic number?

Answer 8

The atomic number = the number of protons (which is the same as the number of electrons)

Question 9

What is the algebraic symbol for atomic number?

Answer 9

Z

Question 10

Why do elements have the same number of protons and electrons?

Answer 10

They’re neutral. They have no overall charge. Protons are positive charge and electrons are negative charge.

Question 11

Are atoms in the periodic table neutral?

Answer 11

Yes. They have the same number of protons and electrons.

Question 12

How do atoms become ions?

Answer 12

Atoms can lose or gain electrons to become ions.

Question 13

Atoms can also exist with different number of neutrons. What do we call these?

Answer 13

Isotopes.

Question 14

Do isotopes have the same atomic number but different mass numbers OR the same mass numbers but different atomic numbers?

(Atomic number = the number of protons/electrons
& Mass number = the number of protons and neutrons)

Answer 14

Isotopes are atoms that exist with a different number of neutrons. So, they will have the same atomic number (number of protons/electrons) but different mass numbers (the number of protons and neutrons added together).

Question 15

How do we name isotopes?

Answer 15

We name isotopes by their mass number, so two isotopes of carbon are carbon-12 (mass number 12) and carbon-14 (mass number 14).

Carbon-12 will have 6 protons and 6 neutrons.
Carbon-14 will have 6 protons and 8 neutrons.

Question 16

Why is the mass number you see on the periodic the table that number?

Answer 16

The mass number you see on the periodic table is an average of all the isotopes of that element. It takes into account the amount of each isotope found on Earth. As most of the carbon on Earth is carbon-12, the mass number on the periodic table is much closer to this than 14. On precise periodic tables, you will find the mass number of carbon is 12.0107.

Question 17

How many stable isotopes do elements usually have?

Answer 17

One or two stable isotopes.

Question 18

How many stable isotopes does carbon have?

Answer 18

Two (carbon-12 and carbon-13)

Question 19

Any remaining isotopes that aren’t stable are what? Give an example.

Answer 19

Any remaining isotopes that aren’t stable are unstable or radioactive (for example, carbon-14).

Question 20

What does it mean if an isotope is unstable or radioactive?

Answer 20

This means their nucleus decays (breaks apart).

Question 21

Is radioactive decay a random process? What does this mean?

Answer 21

Yes. This means that we don’t know when a nucleus will decay, and we can’t make it do so by any means (changing physical conditions i.e. temperature). We can’t make a nucleus decay faster or slower.

Question 22

When a nucleus does decay during the process of radioactive decay, what does it release?

Answer 22

It releases energy and ionising radiation.

Question 23

Why is ionising radiation named so?

Answer 23

Because it ionises atoms it hits (makes them lose or gain an electron).

Question 24

What are the four types of ionising radiation?

Answer 24

Alpha particles, beta particles, gamma rays or neutrons.

Question 25

During ionising radiation, what happens to the nucleus?

Answer 25

The nucleus changes in to a new element (normally).

Question 26

What health issues can ionising radiation cause?

Answer 26

DNA damage and cancer.

Question 27

We are constantly subjected to low-level radiation which can come from natural and manmade sources. It's always present. What is this background radiation caused by?

Answer 27

Radioactive materials in rocks and soil. It's also present in cosmic rays (waves from the big bang). Manmade sources include some medicines, food and fallout from nuclear bomb tests. Nuclear power plants use radioactive isotopes to produce electricity. This and the nuclear waste left over is another source of background radiation.

Question 28

What is the algebraic symbol for alpha particles?

Answer 28

(α)

Question 29

What are alpha particles?

Answer 29

Alpha particles are helium nuclei without the electrons orbiting them. They are just 2 protons and 2 neutrons.

Question 30

Are alpha particles slow and large or fast and small? What distance can they travel before bashing into air particles?

Answer 30

Alpha particles are quite slow and large. They travel about 5cm before bashing into air particles, so are strongly ionizing.

Question 31

Are alpha particles likely to bash into atoms, knocking off electrons as they do (ionising them)? Why or why not?

Answer 31

Yes, they're highly likely to bash into atoms, knocking off electrons as they do (ionising them). This is because they travel about 5cm before bashing into air particles, so are strongly ionising.

Question 32

Do alpha particles penetrate materials much? Why or why not?

Answer 32

No, because they have no electrons, alpha particles are positively charged. This means they can be deflected (forced to change direction) by electric and magnetic fields.

Question 33

What is the algebraic symbol for beta particles?

Answer 33

(β-)

Question 34

What are beta particles (β-)?

Answer 34

Beta particles are an electron which has been emitted from the nucleus when a neutron turns into a proton and electron.

Question 35

Beta particles are an electron which has been emitted from the nucleus when a neutron turns into a proton and electron. What does this cause in regards to the number of electrons, protons and neutrons, and in turn the atomic number and the mass number?

Answer 35

This causes the number of protons in the nucleus to rise by 1. The mass number remains the same. The atomic number increases by 1.

Question 36

Are beta particles fast and small or slow and large?

Answer 36

Beta particles are small and fast.

Question 37

Do beta particles penetrate materials more easily than alpha particles? Why/why not?

Answer 37

Yes, so they are considered to have moderate ionising power. They are just a negatively charged electron so can also be deflected by electric and magnetic fields.

Question 38

What is the algebraic symbol for gamma radiation?

Answer 38

(γ)

Question 39

What are gamma rays?

Answer 39

Gamma rays aren't particles, but electromagnetic waves.

Question 40

Do gamma rays have mass and charge? What does this mean for their atomic number or mass number?

Answer 40

No, they have no mass or charge. They are just energy. This means there is no change to atomic number or mass number.

Question 41

Do gamma rays penetrate into materials?

Answer 41

Gamma rays penetrate far into materials.

Question 42

Are gamma rays weakly ionising or strongly ionising and why?

Answer 42

Gamma rays are weakly ionising because they pass through materials rather than collide.

Question 43

What health issues can gamma rays cause?

Answer 43

Gamma rays can damage DNA and trigger cancer when they do collide.

Question 44

Gamma rays have no charge. Are gamma rays deflected by electrical and/or magnetic fields?

Answer 44

Gamma rays have no charge, so they are not deflected by electrical or magnetic fields.

Question 45

When is gamma radiation emitted?

Answer 45

Gamma radiation is only emitted after alpha or beta decay.

Question 46

What is neutron radiation?

Answer 46

Neutron radiation is the emission (release) of neutrons.

Question 47

Do neutrons have any charge, and what is the mass of a neutron?

Answer 47

No, neutrons don't have charge, and the mass is roughly the same as a proton.

Question 48

What happens to the mass number and atomic number if a neutron is emitted from a nucleus?

Answer 48

If a neutron is emitted from a nucleus, the mass number will reduce by 1 and the atomic number will stay the same.

Question 49

What happens to the mass number and the atomic number if a neutron is absorbed by a nucleus?

Answer 49

The mass number will increase by 1 and the atomic number won't change.