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Chemistry 90% > Complex Chemistry/ Nuclear Chemistry > Flashcards

Complex Chemistry/ Nuclear Chemistry Flashcards

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1
Q

Radiation

A

Emission of subatomic particles or high energy electromagnetic radiation

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2
Q

Nuclear Decay

A

Integration in the nucleus. Continuous, spontaneous random process

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3
Q

Radioisotope/ radio nuclide

A

A nucleus that changes its structure spontaneously and continuously while emitting characteristics types of ration

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4
Q

3 types of emissions

A

Alpha/ Beta/ Gamma

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5
Q

Alpha emission

A
  • Short range, highest ionization.
  • Stopped by thin card, cannot penetrate skin, causes severe burn
  • A decrease by 4, Z decrease by 2
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6
Q

Beta emission – 3 types:

A

Negatron Decay / Positron Decay/ Electron Capture

- Penetrate further than alpha, stopped by metal

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7
Q

Negatron Decay

A
  • Emission of high speed, energetic e- or negatively charged beta particles
  • Neutron to proton transition n > p + (-1e) + v (v = antineutrino)
  • Z decrease by 1, A stay the same
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8
Q

Positron Decay

A
  • emission of high energetic positively charged electrons (beta particles, antiparticle)
  • Proton to neutron transition p > n + (+1e) + v (v = neutrino)
    (Antiparticle meets corresponding particle = annihilation)
  • +1e + -1e > 2 gamma distinctive energy of 0.51 MeV
  • Z decrease by 1, A stays the same
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9
Q

Electron Capture

A
  • Proton to neutron transition p + (-1e) > n + x-rays

- Z decreases by 1, A remains the same

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10
Q

Gamma radiation

A
  • Short wavelength, high energy electromagnetic radiation
  • Very penetrating; stopped by thick lead plate or concrete shielding
  • Emission of alpha and beta normally results in an excited state nuclide. Transition from excited state to ground state results in emission of gamma radiation
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11
Q

Nuclide

A

An atom of a particular isotope

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12
Q

Radioactive decay

A

Parent nuclide > daughter nuclide + nuclear radiation
Ratio of p+ & n0 change in parent nuclide > new elements formed
(p+ gives identity; e- gives personality)

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13
Q

Radioactivity

A

Unstable atom nuclei is spontaneously integrating and simultaneously giving out nuclear radiation

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14
Q

Chemical reaction vs Nuclear reaction

A
  • Atoms are re- arranged to form new molecules in CR
  • Different isotopes of the same element undergo same CR
  • Different isotopes of the same element DO NOT all undergo the same NR
  • Atoms are destroyed or created in NR
  • Atomic mass change in NR
  • Energy changes much greater in NR (E=mc^2)
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15
Q

Nuclear stability

A

Base on n:p ratio

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16
Q

Z < 20

A

stable ratio normally 1:1

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17
Q

Z > 20

A

1:1 to 1:1.5 is normally stable range

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18
Q

A > 209

A

major instability

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19
Q

Z > 83

A

instability

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20
Q

A > 238,

A

spontaneous fission

21
Q
  • Beta emission more likely for ______elements

- Alpha emission more likely for ______elements

A

Beta: lighter

Alpha: heavier

22
Q
  • Few nuclides with Z < 60 will emit _________
A

alpha particles

23
Q
  • Elements with_______Z number most abundant

- the only one of the 8 most abundant elements with odd Z number ?

A

an even Z number

Al

24
Q

Nuclear Fission

A

the process of splitting the atoms

25
Q

Nuclear Fusion

A

a nuclear reaction in which two or more atomic nuclei collide at very high speed and join to form a new type of atomic nucleus

26
Q

Radioactivity half life equation

A

T(1/2) = 0.6931/ λ

27
Q

Half - life

A

the time taken for half of the radioactive nuclei to decay.

28
Q

Radioisotopes

A

Isotopes that are radioactive

29
Q

Becquerel

A
  • the activity of a quantity of radioactive material in which one nucleus decays per second
  • 1 disintegration per second SI unit= 1 Bq
30
Q

Activity =

A
  • 1 Curie unit (Ci)

- the activity of 1g of pure (226) Ra= 3.7 x 10^10 Bq

31
Q

Specific activity

A

activity per unit mass

32
Q

Dosage is _____

A

2mSv per year - 20% own bodies, 30% cosmic/ space, 40% Radon, 10% medical exposure

33
Q

Absorbed dose

A

amount of energy SI unit Gray (Gy). 1 Gy = 1JKg^-1

34
Q

Rad

A

old unit of Gy for absorbed dose

1 Gy= 10 Rad

35
Q

Dose equivalent measured in

A

Sieverts (Sv)
Old unit was Rem
1Sv = 100 Rem

36
Q

Sv =

A

Gy x Q factors

37
Q

Q factors

A

Biological effectiveness and must take into account type of radiation and types of tissues affected
Different tissues have different Q factors

38
Q

alpha radiation has Q factor of _______

A

x 20 greater than either beta or gamma radiation

39
Q

3 methods of detection & measurement of radioactivity in the environment

A

~ Geiger- Muller tube - ionisation of gases
~ Scintillation Techniques - excitation of liquids or solids
~ Dosimeters - induction of chemical change

40
Q

Activity

A

no of nuclear disintegrations per sec (1 Becquerel= 1 disintegration/ second)

41
Q

2 types of Radioactivity measurement

A

Differential - individual emissions per unit time - quantitative analytical work
Integral - total cumulative effect - dosimetry

42
Q

For consistent radioactivity measuring results,_______

A
  • background needs to be measured
  • Significant number of measurements to be made - due to random nature of process of decay
  • Statistical assessment of results required
43
Q

Counting Efficiency (E)

A

Observed counts from detector/ activity from source

44
Q

Factors affect E (__________)

A

Counting efficiency

  • Geometrical position of counter wrt to source
  • Absorption of radiation by any material between source and detector
  • Limitations of detector
  • Dead time losses
45
Q

Measurements of Environmental Radioactivity

A

Measurement of radioactivity in water, air, many foods and animals done routinely

46
Q

3 Environmental Radioactivity measuring method

A

Radiotracer methods
Activation Methods
Isotope Dilution Methods

47
Q

Medical application techniques

A
  • Positron emission tomography
  • Single photon emission computed tomography (SPECT)
  • Cardiovascular imaging
48
Q

Nuclear medicine imaging is useful for detecting

A
  • Tumors
  • Blood cell disorders
  • Inadequate functioning of organs

Chemistry 90% (7 decks)

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