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Physics > The Atom, Radioactivity And The Nucleus > Flashcards

The Atom, Radioactivity And The Nucleus Flashcards

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1
Q

Describe Rutherford’s gold foil experiment

A

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°

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2
Q

What did Rutherford conclude

A

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

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3
Q

What does the Bohr model show

A

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

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4
Q

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

A

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

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5
Q

What happens when atoms receive energy

A

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

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6
Q

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

A

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

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7
Q

What are the two types of spectra

A

Continuous and line

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8
Q

What causes a continuous emission spectrum

A

White light

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9
Q

How can you create a line spectrum

A

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

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10
Q

What are atoms made of

A

Protons, Neutrons and Electrons

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11
Q

What is the atomic number

A

The number of protons and electrons in an atom

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12
Q

What defines the mass number

A

The number of Protons and Neutrons in the atom

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13
Q

What variable defines what element an atom is

A

Number of Protons

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14
Q

What occurs when you add Neutrons to an atom

A

It creates isotopes of that element

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15
Q

What is the result of adding electrons

A

An ion is formed

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16
Q

Define Radioactivity

A

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

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17
Q

What is an alpha particle

A

Helium nucleus, 2 protons 2 neutrons

18
Q

What is a beta particle

A

Highly charged electron

19
Q

What is gamma radiaton

A

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

20
Q

List radiation in order of least to greatest penetrative power

A

Alpha, beta, gamma

21
Q

List radiation in order from least to most massive

A

Gamma, beta, alpha

22
Q

What is required to block alpha particles

A

Sheet of paper or 8cm of air

23
Q

What is required to block beta particles

A

3mm or aluminium or 1m of air

24
Q

What is required to block gamma radiation

A

Several meters of concrete or lead, goes forever in air

25
Q

What can radiation be used for

A

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

26
Q

What are the two devices used to detect radiation

A

Geiger-Muller tube and Solid State detectors

27
Q

What is the difference between the two detection methods for radiation

A

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

28
Q

How does the Geiger-Muller tube work

A

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.

29
Q

What is the rate of decay

A

The number of nuclei that decay every second measured in Bq

30
Q

What does the law of radioactive decay state

A

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

31
Q

Define a half life

A

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

32
Q

What is the formula to find n half lifes

A

1/2^n

33
Q

How to calculate the half life using the decay constant

A

T1/2 = ln2/lambda

34
Q

What reactions result in nuclear energy

A
  1. Radiation from nuclei in the form of alpha, beta and gamma
  2. Nuclear Fission
  3. Nuclear Fusion
35
Q

What is Einstein’s mass-energy equivalence formula

A

E = mc^2

36
Q

What does Einstein’s mass energy equation show

A

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

37
Q

When is energy released in nuclear Fission

A

When the mass of the reactants is greater than the products

38
Q

When is energy consumed in nuclear Fission

A

When the mass of the reactants are lower than the products

39
Q

What is nuclear Fission

A

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

40
Q

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

A

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

Physics (4 decks)

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