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Chem 2 Heider > Ch 19 - Radioactivity and Nuclear Chemistry > Flashcards

Ch 19 - Radioactivity and Nuclear Chemistry Flashcards

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1
Q

nuclear processes often result in

A

one element changing into another frequently emitting a tremendous amount of energy

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2
Q

Radioactivity

A

the emission of subatomic particles of high energy electromagnetic radiation by the nuclei of certain atoms

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3
Q

Radioactive

A

atoms which emit subatomic particles of high energy electromagnetic radiation by their nuclei

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4
Q

phosphorescence

A

long lived emission of light that sometimes follows the absorption of light by certain atoms and molecules
- it’s the glow in glow in the dark toys

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5
Q

Antoine-Henri Becquerel

A

French scientist in 1896 who hypothesized phosphorescence was related to X-rays.

	- used the term uranic(from uranium in the crystal) rays to describe what he thought was an X-ray pattern on a photographic plate from a potassium uranyl sulfate crystal wrapped in black cloth
		- later recanted his hypothesis when he discovered the pattern was created in sunlight or without it
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6
Q

Marie Sklodowska Curie

A

one of first women in France to pursue doctoral work

 discovered two new elements(polonium and radium) which emitted uranic rays
		-  renamed uranic rays to radioactivity
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7
Q

Becquerel, Curie and he husband were awarded

A

the Nobel prize in physics in 1903 for discovering radioactivity

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8
Q

Marie Curie won a second Nobel prize in

A

1911 for discovering the two new elements in her research

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9
Q

Main types of radioactivity

A
  • alpha(a) and beta(B) decay

- gamma(y) ray and positron emission

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10
Q

electron capture

A

some unstable atomic nuclei can attain greater stability by absorbing an electron from one of the atoms own orbitals

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11
Q

isotope notation review

A
  • A/Z(X)
    - A = mass number
    - the sum of the number of protons and the number of neutrons in the nucleus
    - Z = atomic number
    - the number of protons in the nucleus
    - X = chemical symbol
    - N = A – Z
    - the number of neutrons or the difference that must be covered due to a lack of protons
    - 21/10(Ne)
    - 21 – 10 = 11 neutrons and 10 protons
    - 20/10(Ne)
    - 20 – 10 = 10 neutrons and 10 protons
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12
Q

Nuclide

A

a specific isotope(or species) of an element when discussing nuclear properties

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13
Q

the main subatomic particles, protons, neutrons, and electrons use similar notation to elements

A
  • 1/1(p), 1/0(n),0/-1(e)
    - the bottom number for protons and neutrons represents the proton total
    - electron bottom number is different
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14
Q

Alpha(a) Decay

A

occurs when an unstable nucleus emits a particle composed of two protons and two neutrons

	- identical to a helium-4 nucleus
	- 4/2(He)
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15
Q

nuclear equation

A

an equation that represents nuclear processes such as radioactivity

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16
Q

when an element emits an alpha particle, the number of protons

A

in its nucleus changes transforming the element into a different element

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17
Q

parent nuclide

A

the original atom

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18
Q

daughter nuclide

A

the product of the decay

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19
Q

the alpha particle is by far the most massive of all particles emitted by radioactive nuclei

A
  • has the greatest potential to interact and do damage other molecules, including biological
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20
Q

ionizing power

A

the ability of radiation to ionize other molecules and atoms

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21
Q

alpha has the highest

A

ionizing power

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22
Q

penetrating power

A

the ability to penetrate matter

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23
Q

alpha has the LOWEST penetrating power due to largest size

A
  • can be stopped by paper, cloth, air and subsequently a low level alpha emitter that remains outside the body is relatively safe
    - if ingested it becomes very dangerous as there is direct contact with organ tissue
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24
Q

Beta(B) Decay

A

occurs when an unstable nucleus emits an electron

  • if a nucleus changes to a proton it spits its electron out
    - neutron -> proton + emitted electron
    - 1/0n->1/1p + 0/-1e
    - the -1 reflects the charge of the electron
    - the atomic number will change by 1 because it now has an additional proton
    228/88Ra->228/89Ac+0/-1e
    - the equation is balanced
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25
Q

Beta(B) Decay ionizing and penetrating power

A

lower ionizing power but higher penetrating power than alpha particles

		- requires something like a sheet of metal or thick piece of wood to stop
		- possesses a higher risk outside the body than an alpha emitter but lower damage if ingested than an alpha emitter
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26
Q

Gamma(y) Ray Emission

A

electromagnetic radiation, high-energy(short wavelength) photons

	- significantly different than alpha and beta decay
	- o/oy
		- no charge or mass
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27
Q

gamma rays do not change the

A

mass or atomic number of the element

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28
Q

gamma rays are usually

A

emitted in conjunction with other types of radiation

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29
Q

gamma rays ionizing and penetrating power

A
  • lowest ionizing power but higher penetrating power
    - requires several inches of lead shielding or thick slabs of concrete to stop
    - most dangerous outside the body and least dangerous if ingested
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30
Q

Positron Emission

A

occurs when an unstable nucleus emits a positron

  • 1/1p -> 1/0n + 0/+1e
    - when an atom emits a positron its atomic number decreases by 1
    - 30/15P->30/14Si+0/+1e
    - similar to beta particles in their ionizing and penetrating power
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31
Q

positron

A

the antiparticle of the electron with the same mass as an electron but the opposite charge

		- if a positron and electron collide they annihilate each other releasing energy in the form of gamma rays
		- a proton is converted into a neutron and emits a positron
			- proton-> neutron + positron
			- 0/+1e
  • 1/1p -> 1/0n + 0/+1e
    - when an atom emits a positron its atomic number decreases by 1
    - 30/15P->30/14Si+0/+1e
    - similar to beta particles in their ionizing and penetrating power
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32
Q

Electron Capture

A

a particle being absorbed by instead of emitted from an unstable nucleus

	- occurs when a nucleus assimilates an electron from an inner orbital of its electron cloud
	- like positron emission, the net effect of electron capture is the conversion of a proton into a neutron
	- Proton + electron->neutron
	- 1/1p+0/-1e->1/0n
	- the atomic number will decrease by 1 as a proton is lost
		- 92/44Ru+0/-1e->92/43Tc
33
Q

nucleus is a collection of

A

protons and neutrons

34
Q

the strong force

A

a fundamental physics concept which attracts all nucleons(protons and neutrons) together over a very short distance

35
Q

nucleon

A

protons and neutrons

36
Q

protons and neutrons occupy energy levels inside the nucleus similar to how electrons function around the nucleus

A
  • this is why adding more neutrons does not continue to stabilize a nucleus as the energy payback from the strong force is not enough to compensate the increased energy state
37
Q

the ratio of neutrons to protons(N/Z) is very important to determining

A

nuclear stability

38
Q

valley(island) of stability

A

the graphical representation of stable nuclei

	- 1-20 protons = 1/1 ratio
	- 21-40 protons = N/Z = 1.25
	- 41-80 protons = N/Z = 1.50
	- 84+ stable nuclei do not exist
	- Bismuth(83 protons) is the heaviest element with a stable nuclei
39
Q

N/Z too high

A

have too many neutrons and tend to convert neutrons to protons via Beta(B) decay

40
Q

N/Z too low

A
  • convert protons to neutrons via positron emission or electron capture
    - Alpha decay also raises the N/Z ratio for nuclides in which N/Z>1 but a much smaller
41
Q

magic number

A

the uniquely stable nucleons with certain numbers

	- N or Z = 2,8,20,28,50,82
	- N = 126
42
Q

atoms with a Z(# prtons)>83 are

A

radioactive and decay

43
Q

an atom will continue to decay until

A

a stable nuclide is reached

44
Q

Film-badge Dosimeters

A

consist of photographic film held in a small case that is pinned to clothing

	- worn by individuals who regularly work around radiation, collected regularly to and processed to monitor a persons exposure
	- more exposure of the film the more radioactivity the person has been exposed to
45
Q

Geiger-Muller Counter

A

instrument(Geiger counter) which passes particles emitted by radioactive nuclei through an argon filled chamber

	- creates a trail of ionized argon atoms which electricity is passed through and heard by an audible click noise
	- more clicks is more radiation
46
Q

Scintillation Counter

A

radioactive emissions pass through a material(NaI or CsI) that emits ultraviolet or visible light in response to excitation by energetic particles
- the light is detected and turned into an electrical signal which can be read on a meter

47
Q

Rate = kN

A
  • N = number of radioactive nuclei

- k = rate constant

48
Q

half life

A

the time it takes for one half of the parent nuclides in a radioactive sample to decay to the daughter nuclides

49
Q

t1/2 =

A

0.693/k

50
Q

a short half life means

A

decays quickly

51
Q

the integrated rate law

A
  • ln([A]t/[A]0) = -kt
    - ln(Nt/N0) = -kt
    - ln(rate(t)/rate0)=-kt
52
Q

radiocarbon dating

A

technique devised in 1949 by Willard Libby to estimate the ages of fossils and artifacts

53
Q

nuclear fission

A

the splitting of uranium atoms(U-235 isotope) releasing a great amount of energy

54
Q

chain reaction

A

neutrons produced by the fission of one uranium nucleus would induce fission in other uranium nuclei
- self amplifying chain capable of producing quite a bit of energy

55
Q

critical mass

A

there must be a large amount of U-235 to create a self sustaining chain reaction to make a bomb

56
Q

a nuclear power plant cannot become

A

a nuclear bomb

57
Q

nuclear fusion

A

the combination of two light nuclei to form a heavier one

58
Q

both fusion and fission emit

A

large amounts of energy because they both form daughter nuclei with greater binding energy energies per nucleon than the parent nuclei

59
Q

nuclear fusion is the energy source of

A

the stars

60
Q

nuclear fusion is the basis for modern nuclear weapons

A
  • hydrogen bombs

- up to 1000 times the explosive force of the first atomic bomb

61
Q

fusion reactions require two positively charged nuclei fuse together requires

A

extremely high temperatures

62
Q

a fusion bomb has a small fission bomb detonated first to create

A

the temperatures necessary for fusion

63
Q

fusion produces about

A

10 times the energy per gram of fission

64
Q

in nuclear reactions matter can be

A

converted to energy

65
Q

E = mc^2

A
  • E = energy
    - m = mass lost
    - c is the speed of light
66
Q

fission produces over a

A

million times more energy per mole than a chemical process

67
Q

mass defect

A

the difference in mass of the reactants to products

- exist in all stable nuclei

68
Q

nuclear binding energy

A

the energy corresponding to the mass defect, obtained from E-mc^2
- the mount of energy required to break apart the nucleus into its component nucleons

69
Q

1amu =

A

931.5MeV

70
Q

a higher binding energy yields a more

A

stable(lower potential energy) nuclide

71
Q

transmutation

A

nuclear reactions transform one element into another

72
Q

linear accelerator

A

an accelerator in a straight line

73
Q

cyclotron

A

an accelerator in two semi circles that spirals a particle out towards a target

74
Q

3 types of radiation effects

A
  • acute radiation damage
    - increased cancer risk
    - genetic effects
75
Q

1 gray(Gy) = 1 J/kg body tissue

A

1 rad = .01J/kg body tissue

76
Q

biological effectiveness factor(RBE = relative)

A

a correction factor

- usually multiplied by the dose in rads to obtain the dose in a unit called rem

77
Q

rem – roentgen equivalent man

A

(dose rads)(BEF) = dose in rems

78
Q

on average we are exposed to 310 mrem of radiation per year from natural sources

A
  • a majority of it from radon

Chem 2 Heider (9 decks)

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