P7 - Radioactivity

Question 1

What are the two types of Decay?

Answer 1

Alpha and Beta

Question 2

What is the equation for Alpha Decay?

Answer 2

4
+ α
2

Question 3

What is the equation for Beta Decay?

Answer 3

0
+ e
-1

Question 4

Write a decay equation for the decay of iron-59 by beta emission.

Answer 4

59 59 0
Fe –> Co + e
26 27 -1

Question 5

What is the Half Life of a radioactive element?

Answer 5

It is the time that it takes half the atoms in a sample to decay.

Question 6

What is radio active decay?

Answer 6

Some atomic nuclei are unstable. The nucleus gives out radiation as it changes to become more stable. This is a random process called radioactive decay.

Question 7

What is Activity?

Answer 7

Activity is the rate at which a source of unstable nuclei decays. Activity is measured in becquerel (Bq)

Question 8

What are the Characteristics of Alpha Radiation?

Answer 8

Type : Subatomic Parcticle 
Compositrion : 2 protons, 2 neutrons 
Charge : + 2e
Relative Mass : 4
Characteristics : High energy (fast moving)

Question 9

What are the Characteristics of Beta Radiation?

Answer 9

Type : Subatomic particle 
Compositrion : 1 electron
Charge : -1e
Relative Mass : 1/2000
Characteristics : Very high speed (nearly speed of light)

Question 10

What are the Characteristics of Gamma Radiation?

Answer 10

Type : Electromagnetic Wave
Charge : 0
Relative Mass : 0
Characteristics : High frequency (EM waves)

Question 11

What is Ionisation?

Answer 11

The process of atoms becoming ions.

Question 12

Out of the Ionising Radiation which is the most to least on Ionising Power?

Answer 12

1. Alpha Radiation (Most)
2. Beta Radiation (medium)
3. Gamma Radiation (Low)

Question 13

Out of the Ionising Radiation which is the most to least on Penatrive Power?

Answer 13

1. Gamma Radiation (Most)
2. Beta Radiation (medium)
3. Alpha Radiation (Low)

Question 14

What is Radioactive Decay?

Answer 14

Random

Question 15

An ancient human was found in a peat bog in Ireland. You are given a 20g sample which has an activity of 4 counts per second. A 10g sample when living would have had a count rate of 8 counts per second. How long ago did the man from the bog die? Carbon - 5700 years

Answer 15

8 x 2 =16 counts
16/2 = 8 - 1 half life
8/2 = 4 - 2 half life

2 x 5700 = 11400 years

Question 16

What is the half-life equations?

Answer 16

Count Rate after Half-Lives (n) = Count Rate Before / 2^n

Question 17

What is the radius of an Atom?

Answer 17

1 × 10^-10 metres

Question 18

What where the observation and interpretations made after the Earnest Rutherford Gold Foil experiment?

Answer 18

Most alpha particles through the foil undefected —> The atom is mostly empty space.
Some alpha particles are defected by small angles —> The nucleas is positively charged as its the alpha particles.
Occasionaly an Alpha particle travels back from the foil —-> The nucleas carries most of the Atoms mass.

Question 19

What did Niels Bohr discover?

Answer 19

Elcectrons exist in different ‘energy levels’ (shells).

Question 20

What did James Chadwick dicover?

Answer 20

Neutrons

Question 21

What did Joseph Thompson discover?

Answer 21

The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it.

Question 22

What is the top number and bottom number of an Element in a periodic table?

Answer 22

Mass Number - Top

Atomic Number - Bottom

Question 23

How does the electron arrangement change?

Answer 23

• The absorption of electromagnetic radiation (move further from the nucleus; a higher energy level)
• The emission of electromagnetic radiation (move closer to the nucleus; a lower energy level).