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Chemistry > Radioactivity > Flashcards

Radioactivity Flashcards

0
Q

Name the types of radiation

A

Alpha beta and gama

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1
Q

Define radioactivity

A

Radioactivity is defined as the spontaneous breaking up unstable nuclei with the emission of one or more types of radiation

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2
Q

Who discovered radioactivity?

A

Henri Beoquerel

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3
Q

Describe how Henri Beoquerel discovered radioactivity

A

He was studying the effect of sunlight on uranium salt crystals. He left some of the salt wrapped in black paper on a photographic plate. He later noticed that the photographic plate had turned foggy. The uranium salt was giving off some kind of radiation. He investigated the radiation being given off and noticed it was being emitted spontaneously. The process was called radioactivity (giving off rays) and the uranium salt was described as radioactive.

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4
Q

Who investigated the radioactivity of uranium salts in more detail?

A

His colleagues Marie and Pierre Curie

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5
Q

How did Marie and Pierre Curie investigate the radioactivity of uranium salts?

A

They purified the salts and discovered two new elements Dolonium and Redium. The Curies and Bacquerel won the Nobel prize for their work on radioactivity in 1903. Marie received a Nobel prize for chemistry for the discovery of the new elements in 1911 (Pierre was dead)

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6
Q

Define an isotope

A

Atoms of the same element which have the same number of protons but a different number of neutrons

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7
Q

Define a radioactive isotope

A

Radioactive form of an element

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8
Q

What are the 3 types of radiation emitted from isotopes?

A

Alpha, Beta and Gama

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9
Q

Describe the charge of alpha particles

A

Particles with a positive charge

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10
Q

Describe the charge of beta particles

A

Particles with a negative charge

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11
Q

Describe the charge of gama rays

A

Rays which are neutral

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12
Q

What do alpha particles consist of?

Also what is this the same as?

A

2 protons and 2 neutrons
A helium atom 4
HE
2

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13
Q

Are alpha particles fast or slow?

A

Slow

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14
Q

How can alpha particles be stopped?

A

Even as easily by the human hand

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15
Q

What can alpha particles harm humans

A

Can cause cancer when inhaled

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16
Q

Alpha particles are emitted by?

A

Radioactive isotopes

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17
Q

Name a radioactive isotope that emitts alpha particles

A

Americium 241

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18
Q

Where can americium 241 be found?

A

In smoke detectors

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19
Q

Alpha particles are helium nuclei, with positive charge and little penetrating ability. Write the chemical equation to represent this.

A

241 237 4
Am -> Np + He + energy
95 93 2

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20
Q

What do beta particles break down into?

A

Protons and electrons

21
Q

Beta particles are emitted what?

22
Q

When in an atom are beta particles emitted?

A

From the nucleus

23
Q

Are beta particles emitted from the nucleus of an atom fast or slow

A

A fast moving stream

24
Q

Are beta particles more or less penetrative then alpha particles?

A

More penetrative

25
Q

How can alpha particles be stopped?

A

By 5mm thick aluminium foil

26
Q

Can beta particles penetrate the body?

27
Q

Can alpha particles cause cancer?

28
Q

With beta particles the protons remain in the nucleus but explain what happens to the mass and atomic numbers

A

The mass number remains the same but the atomic number increases by 1

29
Q

When the atomic number of a beta particle increases what is formed?

A

A new element

30
Q

Carbon 14 is an example of beta decay! What is it used for?

A

Age determination

31
Q

Give the chemical equation for carbon 14

A

14 14 0
( ➡️ N + e + energy
6 7 -1

e= electron
atomic number increases by 1

32
Q

What are gama rays emitted by?

A

Radioactive isotopes

33
Q

Alpha and beta are particles. What is gama?

34
Q

Do gama rays move fast or slow?

35
Q

How can gama rays be stopped?

A

Only by very thick lead

36
Q

What can gama rays do to the human body?

A

Damage the body and cause cancer

37
Q

Do gama rays have high energy?

38
Q

Are gama rays have electro negative radiation?

39
Q

Write the chemical equation for gama rays

A

60 60
CO ➡️ CO + energy
27 27

Cobalt- 60 used to treat cancer

40
Q

Make a distinction between chemical and nuclear reactions

A

Nuclear reactions involve changes to the nucleus involving protons and neutrons. They cause elements to change into other elements.
Such as alpha and beta decay

Chemical reactions involve changes in the distribution of electrons. The element is not changed.
Such as gama

41
Q

What happens to an isotope that undergoes beta decay

A

The atomic number increases by 1 while the mass number remains unchanged

42
Q

Write an equation for the beta decay of radioactive isotopes
19
O
8

A

19 19 _
O ➡️ F + e
8 9

43
Q

With Alpha decay how much does the mass and atomic numbers decrease?

A

Mass number decrease by 4 and atomic number decreases by 2

44
Q

Write the alpha decay for this equation
231
Pa
91

A

231 227 4
Pa Ac + He
91 89 2

45
Q

Define half life

A

The half life is the time taking for half of the radio isotope to decay

46
Q

Why is the alpha radiation emitted by smoke detectors safe?

A

It cannot penetrate the human body

47
Q

Why won’t you have to replace americium 241 often?

A

It’s half life is 400 years

48
Q

What is carbon 14

A

A radioactive isotope

49
Q

In living things is the ratio of carbon 12 to 14 constant?

50
Q

What happens to carbon 14 after death?

A

After death, carbon 14 decays and the changed ratio plus using its half life is used to find age.

Chemistry (9 decks)

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