Chapter 8

Question 1

Who discovered radioactivity and how?

Answer 1

Henri Becquerel. Left uranium rocks in a dark drawer with photographic paper wrapped in black paper. Rocks damaged the photographic paper

Question 2

Who extracted two new elements from an ore of uranium called pitchblende?

Answer 2

Marie and Pierre Curie. Polonium and radium

Question 3

Name the types of radiation emitted by the nucleus of a radioactive isotope

Answer 3

Alpha particles, α, beta particles, β, and gamma radiation, γ.

Question 4

What are alpha particles made up of?

Answer 4

2 protons and 2 neutrons. Nucleus of a helium atom

4
He
2

Question 5

Characteristics of alpha particles (6)

Answer 5

Two protons and two neutrons 
Positive
Attracted to negative electrode
Stopped by thin sheet of paper
Americium-241
Smoke alarms

Question 6

What are beta particles made up of?

Answer 6

Neutron splits into proton and electron. Electron gets ejected pit at a high speed. Element becomes positive

Question 7

Characteristics of beta particles (6)

Answer 7

High speed electrons
Negative
Attracted to positive electrode
Stopped by 5mm of aluminum
Carbon-14
Carbon dating

Question 8

What is gamma radiation?

Answer 8

Does not consist of particles

High energy electromagnetic radiation emitted by unstable nucleus as it releases excess energy

Question 9

Characteristics of gamma radiation (6)

Answer 9

High energy electromagnetic radiation
No charge
Not attracted toward any charge
Stopped by thick block of lead
Cobalt-60
In radiotherapy for killing cancer cells. Preserve foodstuffs

Question 10

Why is radiation dangerous?

Answer 10

All three types can cause mutations in the DNA of genes leading to cancer

Question 11

Nuclear reaction

Answer 11

A nuclear reaction is a process that alters the composition, structure or energy of an atomic nucleus

Question 12

Transmutation

Answer 12

The changing of one element into a new element is known as transmutation and cannot happen with a chemical reaction

Question 13

Differences between chemical and nuclear reactions (4)

Answer 13

Chemical: Nuclear:

• Involves electrons -Changes take place in nucleus
• No new element formed -New element formed
• No release of nuclear radiation -Nuclear radiation released
• Chemical bonds broken&formed -No chemical bonds broken or formed

Question 14

How does an alpha particle affect the atomic number and mass number of an element?

Answer 14

Reduces atomic number by 2

Reduces mass number by 4

Question 15

How does a beta particle affect the atomic number and mass number of an element?

Answer 15

Increases atomic number by 1

No change to mass number

Question 16

How does gamma radiation affect the atomic number and mass number of an element?

Answer 16

No change to atomic number or mass number of an element