Radioactivity (chpt. 8)

Question 1

Who discovered radiation

Answer 1

Henry Becquerel

Question 2

What elements did Pierre and Marie curie discover

Answer 2

Polonium
Radium

Question 3

Radioactivity

Answer 3

The spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation

Question 4

Alpha particles

Answer 4

Groups of 2 protons and 2 neutrons (helium nucleus)
Emitted from the unstable nucleus of a radioactive element thus making it more stable

Travel relatively slowly due to large mass
Deflected by electric and magnetic fields

Question 5

Beta particles

Answer 5

Fast-moving electrons
Formed when a neutron from an unstable nucleus is changed into a proton and an electron
The electron (beta particle) is ejected from the nucleus

Question 6

Gamma radiation

Answer 6

Most dangerous
High-energy electromagnetic radiation

Travels at the speed of light
High penetrating ability

Question 7

Nuclear reaction

Answer 7

A process that alters the composition, structure or energy of an atomic nucleus

Question 8

Chemical vs nuclear reaction

Answer 8

Electrons involved VS nucleus involved
No new element formed VS new element formed
No release of nuclear radiation VS release of nuclear radiation
Chemical bonds broken & formed VS no chemical bonds broken & formed

Question 9

Half-life

Answer 9

The half-life of an element is the time taken for half of the nuclei in any given sample to decay

PRACTICE

Question 10

Isotopes

Answer 10

Atoms of the same element which have different mass numbers due to the different number of neutrons in the nucleus

Question 11

Radioisotope

Answer 11

Radioactive isotope

Question 12

Uses of radioisotopes (x3)

Answer 12

MEDICAL USES
gamma radiation can sterilise medical equipment by destroying germs

FOOD IRRADIATION
bacteria, moulds, yeasts grow on food and cause spoilage. Gamma rays can kill these disease-carrying organisms (not suitable for all foods)

ARCHAEOLOGICAL USES
radiocarbon dating - a technique used to determine the age of an object containing carbon. It is based on the ratio of carbon-14 to carbon-12 in the object
carbon-14 is radioactive and is taken in by animals through their food

Question 13

What happens when an atom loses an alpha particle

Answer 13

Becomes element two places before it in periodic table
-4
-2

Question 14

What happens when an atom loses a beta particle

Answer 14

Changes into an atom of the element one place after it in the periodic table
+0
+1

Question 15

Radioactivity

Answer 15

The spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation

Question 16

Describe the changes that occur in the nucleus of an atom during alpha decay

Answer 16

An unstable nucleus emits two protons and two neutrons as an alpha particle

Question 17

Give 3 properties of alpha particles

Answer 17

• Are positively charged
• low penetrating ability → will be stopped by a sheet of paper
• strongest ionising ability → if inhaled or ingested can be cancerous

Question 18

Describe the changes that occur in the nucleus of an atom during beta decay

Answer 18

A neutron splits into a proton and an electron
Proton remains in nucleus but electron is emitted out as a beta particle

Question 19

Describe the changes that occur in the nucleus of an atom during gamma decay

Answer 19

The structure of the nucleus remains the same but it loses energy to become more stable

Question 20

Why is a new element not formed in gamma decay

Answer 20

No change in structure of nucleus

Question 21

What is background radiation?

Answer 21

Radiation naturally present in the environment

Question 22

What precautions should be taken when working with radioactive material?

Answer 22

• store in a lead container
• minimise time spent with radioactive material
• use protective clothing → gloves, glasses, coat

Question 23

Give an example of a useful radioisotope and indicate one of its uses

Answer 23

Carbon-14 , carbon dating

Cobalt-60 , food irradiation & cancer treatment

Americium-241 , smoke detectors

Question 24

Properties of beta particles

Answer 24

• negative charge
• negligible mass
• high speed
• moderately penetrating