1.2 Basic ideas about atoms - Radioactivity Flashcards

1
Q

Define Radioactivity

A

The spontaneous disintegration of the nucleus of an element

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2
Q

How is radioactivity different to chemical change?

A

The nucleus breaks apart without anything being done to the element in radiactivity

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3
Q

Define radiation.

A

The energy or particles emitted by an element when it disintegrates

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4
Q

Which elements are radiactive?

A

Elements with an atomic number greatr than 93
isotopes of some smaller atoms are also radioactive

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5
Q

When an unstable nucleus splits up (disintegrates) what can it produce?

A

emits radiation
a different atom with a different number of protons is formed

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6
Q

Define radioisotope

A

any isotope of an element which is radioactive

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7
Q

What are the three types of radiation?

A

Alpha, Beta and Gamma

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8
Q

What is alpha made from/ what is the nature of alpha?
What can it pass through?
What is it absorbed by?
Is it affected by elec/magnetic fields?
What is its ionising power?
What is its speed?

A

Made from helium nuclei
Passes through air
Absorbed by paper/skin
Yes it is affected by mag fields
Strong ionising power
Slowest radiation (10% of speed of light)

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9
Q

What is beta made from/ what is the nature of beta?
What can it pass through?
What is it absorbed by?
Is it affected by elec/magnetic fields?
What is its ionising power?
What is its speed?

A

Is a high speed electron
Passes through air/paper/skin
Absorbed by aluminium
Yes it is affected by mag fields
medium ionising power
medium radiation (50% of speed of light)

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10
Q

What is gamma made from/ what is the nature of gamma?
What can it pass through?
What is it absorbed by?
Is it affected by elec/magnetic fields?
What is its ionising power?
What is its speed?

A

is an electromagnetic wave
Passes through air/paper/skin/aluminium/iron
Absorbed by concrete (only reduced)
No it is not affected by mag fields
weak ionising power
fastest radiation (100% of speed of light)

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11
Q

How many neutrons does an alpha particle have?

A

2

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12
Q

How many protons does an alpha particle have?

A

2

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13
Q

When a nucleus emits an alpha particle, by how much does the atomic number of the remaining nucleus decrease?

A

2

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14
Q

When a nucleus emits an alpha particle, by how much does the mass number of the remaining nucleus decrease?

A

4

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15
Q

When an atomic number emits a beta particle, how much does the mass number of the remaining nucleus change by?

A

no change

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16
Q

What is the difference between positron decay and beta decay?

A

In Positron decay a positive charged beta particle is emitted and in Beta decay a negative charged beta particle is emitted

17
Q

What happens in electron capture?

A

an electron from the closest energy level falls into the nucleus

18
Q

what is the equation for electron capture?

A

element + negative charged electron -> new element + neutrino

19
Q

What is the effect of electric and magentic fields on the three types of radiation?

A

Beta particles move faster to the North Pole (positive)
Gamma particles aren’t affected
Alpha particles move slower to the South Pole (negative)

20
Q

Define ‘half-life’

A

the time taken for half the radioactive atoms in a sample of radioactive isotope to decay

21
Q

What is the use of radiocarbon dating?

A

used to calculate the age of plant and animal remains as all living animals absorb carbon which includes a small proportion of radioactive carbon-14

22
Q

What is the use of gamma radiation in the treatment of cancer?

A

the high energy of gamma radiation used to kill cancer cells and prevents a malignant tumour from developing

23
Q

What is the use of tracers in for diagnosis and treatment in medicine?

A

to make soft tissues, such as blood vessels or the kidneys, show up through medical imaging processes

24
Q

what are the uses of dating rocks?

A

Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events

25
Q

what are the uses of sterilising medical equipment?

A

gamma rays efficiently eliminate microorganisms from the medical devices and tissue allografts

26
Q

what are the uses of using radiation to detect leaks in underground pipes?

A

Substances that emit gamma radiation are used as tracers. A radiation detector outside the pipe or above ground is used to track its progress through the pipe.

27
Q

what are the uses of using radiation in fire alarms/smoke detectors?

A

Alpha is weakly penetrating so smoke stops it, the current drops and the alarm goes off.