Nuclear Physics Flashcards

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1
Q

3 isotopes of hydrogen

A

(1 1) Protium
(1 2) Deuterium
(1e 3) Tritium

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2
Q

Fissile material

A

Material that can undergo the fission reaction

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3
Q

The Rutherford model

A

A gold leaf experiment conducted in 1909 by Hans Geiger and Ernest Marsden in which alpha particles were fired at a thin gold leaf (1000 atoms thick). About 1/8000 particles hit the very small, surrounded mostly by empty space, nucleus(containing most of the mass) and were deflected due to the like charge of the alpha particles and protons in the nucleus.

The atoms far away would be unaffected by the forces and continue in a straight path, those closer would be deflected, and closer would completely turn around

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4
Q

Atom

A

Smallest unit of matter that still retains the chemical properties of its elements

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5
Q

Structure of an atom

A

Consists of a central, positive nucleus containing protons and neutrons, orbited by shells/orbitals carrying negative electrons.

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6
Q

What is this referred to as
A=
X=
Z=

A

Nucleic notation
A = (big no.) atomic mass/nucleon no.
X= element symbol
Z= proton/atomic mass

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7
Q

Isotopes

A

Atoms with the same number of protons but different mass numbers. Most radioactive elements exist as isotopes

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8
Q

What happens during nuclear processes

A

The proton and atomic mass number are conserved
The H represents an alpha particle and nuclear radiation

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9
Q

What prevents electrons from falling into the nucleus

A

Their speed

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10
Q

Proton number

A

Number of protons in a nucleus

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11
Q

Proton charge

A

1.6x10*-19

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12
Q

Nucleon number

A

Number of protons and neutrons in an atomic nucleus

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13
Q

Isotope

A

Same proton number different mass number

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14
Q

Nuclide

A

Species of nucleus having particular values of proton and nucleon numbet

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15
Q

2 isotopes of helium

A

3/2 -rare
4/2 - commonest

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16
Q

What does it mean when an isotope is unstable

A

It undergoes radioactive decay, emitting radiation as it changes from one element to another

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17
Q

Nuclear fission

A

When a heavier nucleus divides into 2 smaller ones. Induced by an introduction of a neutron as the neutron has no charge and is not deflected by the positively charged protons in the nucleus.

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18
Q

Radioactive decay

A

The decay of a radioactive substance when its atomic nuclei emit radiation (to become stable?)

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19
Q

Nuclear fusion

A

The process by which energy is released by joining together 2 small light nuclei to form a new heavier nucleus
In the sun: (When 2 energetic hydrogen atoms collide and fuse to form a helium atom)

20
Q

Contaminated

A

When an object has acquired some unwanted radioactive substance

21
Q

Irritated

A

When an object has been exposed to radiation

22
Q

Background radiation

A

Radiation from the environment which we are exposed to all the time

23
Q

Sources that make a significant contribution to background radiation (4)

A

Radon gas (and thoron) in air (main)
Cosmic rays
Food and drink
Rocks and buildings

24
Q

How can ionising nuclear radiation be measured

A

With a detector connected to a counter (geigercounter)

25
Q

Sources of artificial radiation (3)

A

Medical
Fallout from weapons test
Air travel, TV sets

26
Q

Describe the emission of radiation from a nucleus

A

Spontaneous and random in direction

27
Q

What does an atom of a radioactive substance emit

A

Either an alpha or beta particle
Emits energy in the form of a gamma ray (sometimes same time,sometimes later)

28
Q

How fast gamma rays travel

A

At the speed of light

29
Q

Alpha nature

A

Alpha radiation has a high power of ionisation but low penetration

30
Q

Ionisation

A

When a particle becomes radioactively charged by losing/gaining electrons

31
Q

Ionising radiation

A

Radiation that causes ionisation

32
Q

High ionising, low pentrating

A

Alpha (sheet of tissue paper)

33
Q

Low ionising high penetrating (aluminium stops it)

A

Gamma

34
Q

Low ionising, high penetration (lead needed to stop it_

A

Gamma rays

35
Q

Penetrating power

A

How far radiation can penetrate into different materials

36
Q

deflection of α-particles, β-particles
and γ-radiation in magnetic
fields

A

Alpha deflected
Beta deflected more in the opposite direction
Gamma not deflected

37
Q

deflection of α-particles, β-particles
and γ-radiation in electric fields

A

Alpha is positively charged
Beta is negatively charged
Gamma is neutral

38
Q

Effects of ionising nuclear radiations

A

Death in cell due to ionisation
Damage to nucleus results in control mechanisms being broken down and uncontrollable division (tumor + cancer)
Damage DNA if affected cell is a gamete, mutation passed through generations as the egg may not develop at all, or form a genetic disorder

39
Q

Why may isotopes of an element be radioactive

A

Due to an excess of neutrons in the nucleus an/or the nucleus being too heavy

40
Q

Radioactive decay

A

Change in an unstable nucleus that can result in the spontaneous and random emission of alpha/beta particles or gamma rays.

41
Q

What happens to the nucleus during alpha or beta decay

A

It changes to that of a different element

42
Q

Half life

A

Time taken for half the nuclei of the isotope to decay

43
Q

Radioactive tracing

A

Technique that uses a radioactive substance to trace the flow of liquid or gas/ to find the position of cancerous tissue in the body

44
Q

effect of α-decay, β-decay and γ-emissions on the nucleus

A

Increase in stability and reduction in the amount of excess neutrons
Neutron -> proton + electron

45
Q

Beta decay

A

Decay of a radioactive nucleus by emission of a beta-particle (used in carbon dating)

46
Q

how radioactive materials are moved,
used and stored in a safe way

A

Reduce exposure time
Increase distance between source and living tissue
Use shield to absorb radiation
Gloves and tongs
Stored in a container that absorbs as much radiation as possible

47
Q

Uses of radioactivity (5)

A

Thickness control - beta radiation (gm tubes)
Medical (diagnosing and treating cancer and X-rays) - gamma rays IODINE 123
House hold fire alarms - alpha (knows when alpha is being blocked by smoke)
Irritating food to kill bacteria (gamma)
Sterilisation of equipment - gamma rays