The Atom, Radioactivity And The Nucleus

Question 1

Describe Rutherford’s gold foil experiment

Answer 1

Alpha emitter bombarding a thin gold foil with a detector surrounding it, most of the particles pass straight through, some deflect at small angles and a very small number rebound at an angle greater than 90°

Question 2

What did Rutherford conclude

Answer 2

Atom was mostly empty space, nucleus is positively charged, nucleus is small and dense

Question 3

What does the Bohr model show

Answer 3

Atoms have nuclei at the centre and electrons orbit in ‘shells’ around it with different energy values

Question 4

What occurs when an electron falls from a higher energy level to a lower one

Answer 4

A photon is emited with energy equal to that or the difference in energy between the two levels

Question 5

What happens when atoms receive energy

Answer 5

Electrons may get excited and jump energy levels, when the energy is released the electron drops from the excited state

Question 6

How is the frequency of the photon related to the energy diference

Answer 6

hf = E2 - E1, h = planks constant, f = frequency, E = energy

Question 7

What are the two types of spectra

Answer 7

Continuous and line

Question 8

What causes a continuous emission spectrum

Answer 8

White light

Question 9

How can you create a line spectrum

Answer 9

Energised gas release photons as electrons fall from a higher energy to a lower one and each gas emits a unique spectrum

Question 10

What are atoms made of

Answer 10

Protons, Neutrons and Electrons

Question 11

What is the atomic number

Answer 11

The number of protons and electrons in an atom

Question 12

What defines the mass number

Answer 12

The number of Protons and Neutrons in the atom

Question 13

What variable defines what element an atom is

Answer 13

Number of Protons

Question 14

What occurs when you add Neutrons to an atom

Answer 14

It creates isotopes of that element

Question 15

What is the result of adding electrons

Answer 15

An ion is formed

Question 16

Define Radioactivity

Answer 16

Spontaneous breaking up of certain unstable nuclei accompanied by the emission of one or more types of radiation

Question 17

What is an alpha particle

Answer 17

Helium nucleus, 2 protons 2 neutrons

Question 18

What is a beta particle

Answer 18

Highly charged electron

Question 19

What is gamma radiaton

Answer 19

EM radiation in the form of a wave, usually is accompanied by alpha or beta

Question 20

List radiation in order of least to greatest penetrative power

Answer 20

Alpha, beta, gamma

Question 21

List radiation in order from least to most massive

Answer 21

Gamma, beta, alpha

Question 22

What is required to block alpha particles

Answer 22

Sheet of paper or 8cm of air

Question 23

What is required to block beta particles

Answer 23

3mm or aluminium or 1m of air

Question 24

What is required to block gamma radiation

Answer 24

Several meters of concrete or lead, goes forever in air

Question 25

What can radiation be used for

Answer 25

Removing bacteria from food (Food Irradiation), treating cancer (Medical)

Question 26

What are the two devices used to detect radiation

Answer 26

Geiger-Muller tube and Solid State detectors

Question 27

What is the difference between the two detection methods for radiation

Answer 27

Geiger-Muller only detects the presence of radiation and it's amount while the Solid State detectors detect the amount of radiation and which type it is

Question 28

How does the Geiger-Muller tube work

Answer 28

Works on the principle of ionisation of gas particles, the tube contains argon gas with a cathode and anode rod. Between the two electrodes exists a potential difference of several hundred volts. As radiation enters the tube it ionises the gas and creates a current which can be converted into pulses and can be counted.

Question 29

What is the rate of decay

Answer 29

The number of nuclei that decay every second measured in Bq

Question 30

What does the law of radioactive decay state

Answer 30

The activity of a radioisotope is proportional to the number of nuclei that remain undecayed

Question 31

Define a half life

Answer 31

The amount of time taken for 1/2 of the nuclei to decay measured in seconds

Question 32

What is the formula to find n half lifes

Answer 32

1/2^n

Question 33

How to calculate the half life using the decay constant

Answer 33

T1/2 = ln2/lambda

Question 34

What reactions result in nuclear energy

Answer 34

1. Radiation from nuclei in the form of alpha, beta and gamma 2. Nuclear Fission 3. Nuclear Fusion

Question 35

What is Einstein's mass-energy equivalence formula

Answer 35

E = mc^2

Question 36

What does Einstein's mass energy equation show

Answer 36

That mass and energy are interchangeable, that a small change in mass results in a large change in energy

Question 37

When is energy released in nuclear Fission

Answer 37

When the mass of the reactants is greater than the products

Question 38

When is energy consumed in nuclear Fission

Answer 38

When the mass of the reactants are lower than the products

Question 39

What is nuclear Fission

Answer 39

It is the splitting of large nuclei into two similar small nuclei with the release of Neutrons and energy

Question 40

What is the chemical formula for the Fission of U-235

Answer 40

U-235 + n-1 = Ba-141 + Kr-92 + 3n-1 + Q