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chemistry > unit 12 - nuclear chem > Flashcards

unit 12 - nuclear chem Flashcards

1
Q

radioisotopes

A
  • unstable isotopes
  • versions of an element that are NOT stable
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2
Q

all unstable isotopes are…

A

RADIOACTIVE

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3
Q

the nucleus will spontaneousy break down by a means of

A

radioactive decay

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4
Q

decay occurs until

A

a stable isotope of an element forms

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5
Q

table N

A
  • short list (not all) with versions of certain elements that are radioactive
  • ex: C-14 & N-16
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6
Q

remember isotopes are named from…

A
  • their numbers!!
  • the mass numbers are given to you BUT NOT the proton number because that is periodic table
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7
Q

radioactivity: unstable/radioactive atom

A

= spontaneously decay

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8
Q

large neutron to proton ratio

A

more than 1:1 (heavy nucleus)

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9
Q

atomic number what and greater is what

A

atomic number 83 or greater
- all isotopes of these elements are unstable, no version is stable

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10
Q

unstable atoms emit

A

energy and particles

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11
Q

transmutation

A

decay causes the nucleus of an atom to disintegrate and change into the nucleus of another element

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12
Q

natural transmutation

A
  • spontaneous decay
  • when the nucleus of an unstable atom/radioisotope (without intervention) breaks down naturally or by itself
  • in the end the nucleus will trans-mutate or turn into the nucleus of another element
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13
Q

artificial transmutation

A

forced or nonspontaneous decay
- a change in the nucleus of an atom brought about by bombarding the nucleus with high energy particles

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14
Q

there are 4 types of nuclear emissions

A

1) alpha particles
2) beta particles
3) positron particles
4) gamma rays

**use Table O for name, notation, and symbol

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15
Q

alpha particles

A

4 <- mass
He (same as He-4 atom in mass and charge
2 <- charge but they are not the same thing)

  • alpha particles have the lowest penetrating power
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16
Q

what has the lowest penetrating power

A

alpha particles
- they can be stopped by a ream of paper

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17
Q

beta particles

A

0 <- mass
e (same as electron in mass and charge but
-1 <- charge not an electron)

  • beta particles have moderate penetrating power, they can be stopped by a brick
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18
Q

positron

A

0
e
+1
- think of it like a positive electron (not act a thing)
- they too have moderate penetrating power

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19
Q

gamma rays

A

0
y
0
- electromagnetic radiation
- (no mass, no charge), just energy
- have the greatest penetrating power, they can be stopped by a sheet of lead

20
Q

alpha decay

A

the emission of alpha particles (helium atom)
- reduces the atomic number by 2 and reduces mass # by 4

21
Q

total mass and charge on the reactant side must equal

A

total mass and charge on the product side

22
Q

beta decay

A
  • the emission of beta particle (like an electron)
  • will result in NO change in the mass # but the atomic # will increase by 1
23
Q

positron decay

A

the release of a positron
- mass number stays same
- atomic #/nuclear charge decreases by 1

24
Q

gamma radiation

A

high energy electromagnetic radiation
- no change in mass or atomic number
- only a reduction in energy
- not a transmutation bc the proton number is not affected, only a loss of energy

25
Q

how dyk its a natural transmutation

A
  • the equations ALL have ONE REACTANT on the left hand side!!
26
Q

artificial transmutation equations

A
  • two reactants, not happening naturally
  • something has HIT the unstable nucleus and caused it to break down
  • happens in nature or caused by scientists in lab
27
Q

half life

A

the TIME it takes for ONE HALF of the nuclei in a sample to decay
- not affected by temp or pressure

28
Q

nuclear reactions

A

small amount of mass is converted into large amounts of energy

29
Q

fission

A

the splitting of a heavy nucleus to produce a lighter nucleus

30
Q

fusion

A

involves the combining of light nuclei to produce a heavier nucleus

31
Q

fission reaction

A
  • slow moving neutron bombards a heavy element (ex: U or Pu)
  • results in an unstable nucleus which splits (undergoes fission)
  • large amounts of energy released
32
Q

what are fission reaction used for

A
  • to generate nuclear power (electricity)
  • to produce nuclear weapons
    **technically total mass of reactants does not equal total mass of products bc mass was used to create energy
33
Q

fusion reaction

A
  • light nuclei fuse/join to form a heavier nucleus
  • high temperature and pressure is needed
    ex: energy produced from sun and stars, produced by hydrogen bomb
34
Q

nuclear reactors

A
  • are devices for controlling nuclear reactions so that energy released by the reaction can be converted to a useful form at a constant rate
35
Q

fission reactors

A
  • produce energy (ex: electrical energy) from the fission of U-235
  • parts: used currently in nuclear plants
  • fuel: uranium-235 **expensive, dangerous
36
Q

fission reactor: moderator

A

slows down neutrons so that they can be captured by U-235 (ex: Graphite)

37
Q

fission reactor: control rods

A

control the supply of neutrons

38
Q

fission reactor: coolant

A

heavy H2O (deuterium), air, He, or CO2

39
Q

fission reactor: shield

A

covers reactor, protects from radiation

40
Q

fusion reactors

A
  • for the future
  • same parts of a fission reactor
  • requires extreme temperatures (10^9)°C
  • runs on inexpensive fuel (*deuterium)
  • clean process: isotopes are stable as opposed to radioactive isotopes made in fission reactions
41
Q

benefits of radioisotopes

A
  • radioactive dating
  • chemical tracers
  • food preservation
42
Q

benefits of radioisotopes: radioactive dating

A
  • uses the ratio of C-12/C-14 to date previously living things
  • U-238/Pb-206 to date geological material (earth age, rocks)
43
Q

benefits of radioisotopes: chemical tracers

A
  • the ability to detect or trace radioactive materials
    ex: I-131 detects and helps treat thyroid conditions
    ex: Tc-99 and Co-60 treats cancer bc they emit gamma rays
    ex: C-14 helps in the study of photosynthesis
44
Q

benefits of radioisotopes: food preservation

A

Co-60 and Cs-137 are being used to kill bacteria in foods

45
Q

disadvantages of radioisotopes

A

● Radioisotopes can kill healthy tissue as well as cancerous cells

● Radiation can lead to mutations that can be inherited

● It is difficult to store fuel and dispose of wastes at a nuclear power plant

  • Radioactive substances contaminate their surroundings for generations, depending on their half life

Ex. 137 90
Cs or Sr
55 38

chemistry (11 decks)

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