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Chemistry > Ch. 11- Nuclear Chemistry > Flashcards

Ch. 11- Nuclear Chemistry Flashcards

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1
Q

radioactive decay

A

the disintegration of an unstable atomic nucleus with spontaneous emission of radiation

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2
Q

radioisotopes

A

atoms or ions with radioactive nuclei

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3
Q

cosmic rays

A

extremely high-energy radiation from outer space

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4
Q

background radiation

A

constantly occurring radiation from cosmic rays, and from natural radioactive isotopes in air, water, soil, and rocks

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5
Q

ionizing radiation

A

radiation that produces ions as it passes through matter; examples= x-rays & nuclear radiation

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6
Q

is our exposure to background radiation harmful?

A

no, the total amount of background radiation to which the average person is exposed is less than 0.5% of the amount that causes symptoms of radiation sickness

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7
Q

how can high levels of ionizing radiation be harmful?

A
  • damages live tissue (white blood cells are most vulnerable)
  • affects bone marrow, causing less red blood cells to be reduced, resulting in anemia
  • induces leukemia
  • causes mutations in DNA
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8
Q

alpha decay

A

emission of an alpha particle by a radioactive nucleus

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9
Q

beta decay

A

emission of a beta particle by a radioactive nucleus

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10
Q

why is beta decay complicated?

A

in beta decay, a neutron within the nucleus is converted into a proton (which remains in the nucleus) and an electron (which is ejected)

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11
Q

gamma decay

A

emission of a gamma ray by a radioactive nucleus

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12
Q

biggest difference between gamma decay & alpha/beta decay

A

different from alpha & beta decay because gamma radiation has no charge and no mass; A (nucleon #) & Z (atomic #) of emitting atom is changed

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13
Q

positron

A

a positively charged particle with the mass of an electron

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14
Q

positron emission

A

a type of radioactive decay that can be envisioned by the change of a proton in the nucleus into a neutron & a positron, with the positron being emitted from the nucleus

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15
Q

what is it about positron emission & electron capture that differentiates them from the 3 common types of radioactive decay (alpha/beta/gamma)?

A

they both result in a decrease of 1 in atomic number, but with no change in nucleon number

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16
Q

what happens after positron emission?

A

the original nucleus has 1 fewer proton & 1 more neutron than it had before, and the emitted positron quickly encounters an electron where both particles are then annihilated & turned into energy (specifically, 2 gamma rays)

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17
Q

electron capture (EC)

A

a type of radioactive decay in which a nucleus absorbs an electron from the first or second shell of the atom, causing the electron to combine with a proton to form a neutron

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18
Q

what happens after EC?

A

eventually an electron from a higher shell drops to the level vacated by the captured electron, which releases an x-ray

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19
Q

half-life

A

the length of time required for one-half of the radioactive nuclei in a sample to decay

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20
Q

half-life

A

the length of time required for one-half of the radioactive nuclei in a sample to decay

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21
Q

becquerel (Bq)

A

a measure of the rate of radioactive decay (isotope’s activity); 1 Bq = 1 disintegration per second

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22
Q

becquerel (Bq)

A

a measure of the rate of radioactive decay (isotope’s activity); 1 Bq = 1 disintegration per second

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23
Q

carbon-14 dating

A

a radioisotopic technique for determining the age of artifacts, based on the half-life of carbon-14

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24
Q

carbon-14 dating

A

a radioisotopic technique for determining the age of artifacts, based on the half-life of carbon-14

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25
Q

which carbon isotopes do we have on Earth & how much of each?

A

carbon-12 (99%) & carbon-13 (1%)

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26
Q

explain the process in which carbon-14 is formed & concentrated in Earth’s atmosphere & living things

A

nitrogen is abundant in Earth’s upper atmosphere & cosmic rays are constantly raining down on Earth

  1. cosmic rays collide with particles in Earth’s atmosphere, emitting high energy neutrons
  2. emitted neutrons collide with nitrogen atoms, which emits a proton, resulting in formation of carbon-14
  3. carbon-14 becomes concentrated in CO2 in Earth’s upper atmosphere
  4. CO2 is then introduced to living things via photosynthesis
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27
Q

what is the half-life of carbon-14?

A

5730 years

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28
Q

how old must an object be for carbon-14 dating to be accurate?

A

100-50,000 years old

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29
Q

transmutation

A

the conversion of one element into another

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30
Q

tracers

A

radioisotopes used to trace the movement of substances or locate the sites of activity in physical, chemical, and biological systems

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31
Q

what do tracers allow us to do?

A
  • detect leaks in underground pipes
  • measure the thickness of sheet material during production
  • determine frictional wear in piston rings
  • determine the uptake of phosphorus and its distribution in plants
32
Q

why do we use radioisotopes to induce mutations?

A
  • exposing seeds or other parts of plants to neutrons or gamma rays increases the likelihood of genetic mutations
    • saves plant populations & improves varieties
  • can render insect populations sterile
    • kills insect populations & limits need for pesticides
  • irradiate food as a method of preservation
    • radiation destroys microorganisms & enzymes that cause food to spoil
33
Q

what can block an alpha particle?

A
  • a sheet of paper

- outer layer of skin

34
Q

what can block a beta particle?

A
  • a sheet of aluminum

- plexiglass

35
Q

what can block a gamma ray?

A
  • a meter of concrete

- several cm of lead

36
Q

is the mass of the starting material the same amount as the mass of the product in chemical reactions that give off heat?

A

no, the starting material loses a small amount of mass when heat is given off, but it’s too small of an amount to be measurable

37
Q

mass-energy equation

A

E=mc2, in which E is energy, m is mass, and c is speed of light

38
Q

binding energy

A

energy that holds the nucleons together in an atom’s nucleus

39
Q

nuclear fusion

A

the combination of two small atomic nuclei to produce one larger nucleus

40
Q

Emilio Segrè

A

(with Enrico Fermi) Italian scientist who conducted an experiment in which Uranium atoms were bombarded with neutrons in an attempt to create elements with higher atomic numbers than Uranium (had the high atomic # at the time)

41
Q

Otto Hahn & Fritz Strassman

A

German chemists who repeated Fermi-Segrè experiment & found Barium isotopes among the reaction products

42
Q

Lise Meiter

A

Austrian physicist who looked over Hahn’s work & discovered that the uranium nuclei had split apart (nuclear fission)

43
Q

Otto Frisch

A

Austrian physicist who coined the name “nuclear fission”

44
Q

nuclear fission

A

the splitting of an atomic nucleus into two smaller ones

45
Q

Enrico Fermi

A

Italian scientist who conducted Fermi-Segrè experiment, received the 1938 Nobel Prize in Physics, and then fled to the U.S.

46
Q

chain reaction

A

a self-sustaining reaction in which one or more products of one event cause one or more new events

47
Q

Leo Szilard

A

one of the first scientists to discover chain reaction

48
Q

what was the importance of the discovery of chain reaction?

A

chain reaction can be extremely dangerous, and if other countries were to become aware of it (specifically Germany during WWII), they could make explosive bombs; it was critical for the U.S. government to take action on such discovery

49
Q

which element has the most stable nuclei?

A

Iron (Fe)

50
Q

Manhattan Project

A

a massive, highly secret research project for the study of atomic energy

51
Q

who launched the Manhattan Project?

A

President Franklin D. Roosevelt (kept secret from VP Harry Truman)

52
Q

what were the focuses of Manhattan Project’s 4 separate research teams?

A
  • sustaining a nuclear fission chain reaction
  • enriching uranium so that it contained about 90% of the fissionable isotope uranium-235
  • making plutonium-239 (another fissionable isotope)
  • constructing a bomb based on nuclear fission
53
Q

which subatomic particle is required for nuclear fission?

A

neutron

54
Q

critical mass

A

a minimum amount of fissionable material required to achieve a self-sustaining chain reaction

55
Q

natural uranium is made of which isotopes?

A

99.27% uranium-238 & 0.72% uranium-235

56
Q

process for enriching uranium with uranium-235

A
    1. a separation method was used to convert uranium into gaseous uranium hexafluoride (UF6)
    1. UF6 was passed through thousands of pinholes
    1. UF6 molecules containing uranium-235 outdistanced other & became concentrated
57
Q

depleted uranium

A

remaining uranium after enrichment process, includes only about 0.2% uranium-235

58
Q

how was depleted uranium once used?

A

used in weapons, it could pierce through metal & cause serious health problems (heart & lungs) if inhaled

59
Q

how is plutonium made?

A

uranium-238 would decay to form neptunium (Np), which would decay to form plutonium (Pu)

60
Q

Glenn T. Seaborg

A

leader of the research team who figured out how to make plutonium (Pu)

61
Q

Robert Oppenheimer

A

leader of research team responsible for constructing nuclear bombs

62
Q

name the sites of the 4 research teams of the Manhattan Project

A
  1. Chicago, IL (sustaining fission chain reaction)
  2. Oak Ridge, TN (enriching uranium)
  3. Hanford, WA (making plutonium-239)
  4. Los Alamos, NM (constructing nuclear bomb)
63
Q

who led the Chicago, IL team of the Manhattan Project?

A

Enrico Fermi

64
Q

which 2 models of atomic bombs were developed?

A
    1. based on uranium-235

- 2. based on plutonium-239

65
Q

how did the uranium-235 atomic bomb work?

A

bomb contained pieces of uranium-235 of subcritical mass plus a neutron source to initiate the fission reaction; when all pieces are forced together using a high explosive, nuclear chain reaction is triggered

66
Q

where were the 3 US atomic bombs dropped?

A
  • 1st bomb was plutonium & was dropped in Alamogordo, NM as a test
  • 2nd bomb “Little Boy” was uranium & was dropped in Hiroshima on 8/6/45, causing over 100,000 deaths
  • 3rd bomb “Fat Man” was plutonium & was dropped in Nagasaki
67
Q

how did WWII end?

A

“Little Boy” and “Fat Man” resulted in Japan surrendering on 8/14/45 & WWII ending

68
Q

radioactive fallout

A

radioactive debris produced by explosion of a nuclear bomb

69
Q

what are the 3 most concerning isotopes in radioactive fallout & what are their half-lives?

A
  1. Strontium-90 (acts as calcium & concentrates in bone, causing bone cancer & leukemia); half-life= 28.5 y
  2. Iodine-131 (concentrates in the thyroid gland, causing damaging side effects in large amounts); half-life= 8 d
  3. Cesium-137 (acts as potassium & concentrates in body fluids, causing damage at high levels); half-life= 30.2 y
70
Q

Linus Pauling

A

won Nobel Peace Prize in 1962 for being a major advocate of banning atmospheric atomic bomb tests

71
Q

when was the nuclear test ban treaty signed?

A

in 1963, signed by major nations (minus France & People’s Republic of China)

72
Q

thermonuclear reactions

A

nuclear fusion reactions that require extremely high temperatures and pressures

73
Q

uses of nuclear energy

A
  • electricity
  • propel sea vessels (mainly military)
  • medical diagnostics/procedures
74
Q

consequences of nuclear energy

A
  • build-up of nuclear waste
  • potential use of spent nuclear fuel for weapons
  • possibility of nuclear plants malfunctioning
75
Q

where is the largest environmental cleanup effort in the US?

A

Hanford, WA

76
Q

what are the 3 nuclear plant malfunctions that have occurred?

A
    1. Three Mile Island (Harrisburg, PA)
      - partial meltdown causing little radioactive fallout
    1. Chernobyl
      - fire & release of radioactivity causing serious radioactive fallout
    1. Fukushima
      - 2011 earthquake caused tsunami waves that flooded the plant & town, causing a partial meltdown, cooling system failure, & serious radioactive fallout

Chemistry (9 decks)

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