Physics D

Question 1

Radius of an atom

Answer 1

1 x 10^-10

Question 2

Isotope

Answer 2

Different forms of the same element with the same number of protons but different number of neutrons

Question 3

Radioactive decay

Answer 3

When unstable atoms randomly emit radiation to become stable

Question 4

Alpha decay

Answer 4

Alpha decay involves the release of a helium nucleus (two protons and two neutrons)
When an alpha particle decays the element forms a new element

Question 5

Alpha properties

Answer 5

• same as a helium nucleus
• has a charge of positive two
• a RAM of 4
• has very weak penetration power
• has a very high ionising effect
• stopped by paper
• range in air is a few cm

Question 6

Beta

Answer 6

Formed when a a neutrons turns into a proton and emits a fast moving electron (beta particle).
Since the element being decayed has essentially gained a proton the atomic number increases changing the element.

Question 7

Gamma

Answer 7

High energy electromagnetic waves emitted from an unstable nuclei
Gamma rays are pure energy with no mass or charge. So nothing changes except an added gamma ray

Question 8

Half life

Answer 8

Average time taken for half the nuclei in a sample to decay.

Question 9

Activity

Answer 9

Number of unstable atoms that decay per second

Question 10

Beta properties

Answer 10

• fast moving electron
• has an electric charge of -1
• ram is very small
• has moderate penetration power
• stopped by plastic
• range in air is a few m

Question 11

Gamma properties

Answer 11

• highly penetrating
• stopped by thick piece of lead
• produce least amount of ionisation
• very far range in air