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CLS3003-B: Chemistry (Semester 1) > L2 - Atomic Structure & Isotopes > Flashcards

L2 - Atomic Structure & Isotopes Flashcards

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1
Q

What 3 main subatomic particles are atoms composed of?

A
  • Electrons (negative)
  • Protons (positive)
  • Neutrons (uncharged)
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2
Q

The diameter of an atom is approximately _______ times larger than that of its nucleus.

A

10,000

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3
Q

Describe the charge of an atom.

A

Neutral

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4
Q

How does an atom become a charged ion?

A

Loss / gain of electrons

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5
Q

What does the centre of the atom (nucleus) have?

A
  • All most all of the atom’s mass

- Composed of atom’s protons and neutrons

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6
Q

What are protons and neutrons called?

A

Nucleons

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7
Q

Define Atomic Number (Z).

A

Number of protons in the nucleus of an atom.

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8
Q

Define Mass Number (A).

A

Sum of the protons and neutrons in the nucleus (Nucleons)

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9
Q

Where are electrons found in an atom?

A

They surround the nucleus

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10
Q

What do electrons occupy?

A

Specific regions in space (orbitals)

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11
Q

What are orbitals grouped into?

A

Shells

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12
Q

How are shells identified?

A

By the principal quantum number (n = 1, 2, 3…)

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13
Q

What does each shell contain?

A

A unique set of orbitals

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14
Q

What are elements with completely filled shells referred to as?

A

Noble gases

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15
Q

What determines the properties of the atom? (e.g. reactivity, ability to form bonds)

A

Electrons

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16
Q

Define isotope.

A

Atom with the same atomic number but different mass number.

Atom with the same number of protons but different number of neutrons.

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17
Q

Describe the properties of isotopes.

A
  • Different atoms of the same elements
  • Same number of protons and electrons
  • Different mass, due to the number of neutrons
  • Same outer electrons and chemical identity = chemical properties are identical
  • Physical properties can differ (e.g. density)
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18
Q

Describe the Kinetic Isotope Effect.

A

Heavier isotopes react slightly more slowly.

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19
Q

Name 3 isotopes of hydrogen.

A
  • Protium
  • Deuterium
  • Tritium
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20
Q

What is the most abundant hydrogen isotope?

A

Protium

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21
Q

Describe the uses of deuterium.

A
  • Used in isotopic labelling experiments

- Useful in NMR spectroscopy

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22
Q

Describe the uses of tritium.

A
  • Radioactive

- Used in labelling experiments

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23
Q

Name 3 isotopes of carbon.

A
  • Carbon-12
  • Carbon-13
  • Carbon-14
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24
Q

Which 2 carbon isotopes are stable?

A
  • Carbon-12

- Carbon-13

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25
Q

Describe the uses of carbon-14.

A
  • Radioactive

- Used for radiocarbon dating

26
Q

Name the 2 isotopes of chlorine.

A
  • Chlorine-35

- Chlorine-37

27
Q

Name the 2 isotopes of bromine.

A
  • Bromine-79

- Bromine-81

28
Q

Define Relative Atomic Mass (Ar).

A

(Of an element) is the weighted average of the individual isotopes.

29
Q

How is measured atomic weight / average atomic weight calculated?

A

(Isotopic Abundance * Isotope Mass Number) / Isotopic Abundance

30
Q

What does ordinary chlorine consist of?

A
  • 3 atoms of Chlorine-35

- 1 atom of Chlorine-37

31
Q

Describe stable isotopes.

A

Remain uncharged indefinitely

32
Q

Describe unstable isotopes.

A
  • Undergo spontaneous disintegration in order to become a stable nucleus
  • Disintegration results in emission of small particles and/or radiation
  • Also called radioactive isotopes
33
Q

Both forms of isotopes can be used as __________ _____ and _______.

A
  • Diagnostic Tools

- Tracers

34
Q

How does mass spectrometry work?

A

Measures the molecular weight of atoms or compounds by observing the mass to charge ratio (m/z) of ions.

35
Q

State the applications of mass spectrometry.

A
  • Determining isotopic abundances

- Identity of small molecules and proteins

36
Q

Upon which principle is mass spectrometry based?

A

Atoms and molecules are converted into ions, which can be separated on the basis of their masses and motions in magnetic / electrical fields.

37
Q

What does the position of peaks on a mass spectrum tell us?

A

Atomic Mass

38
Q

What does peak intensity on a mass spectrum tell us?

A

Relative Abundance

39
Q

Describe how abundance on a mass spectrum is presented.

A

Usually highest abundance is scaled up to 100% - other values are adjusted accordingly.

40
Q

Many stable isotopes are used in __________ ________.

A

Biomedical research

41
Q

Describe what happens during radioactive decay.

A

The nucleus of an unstable radioisotope seeks energetic stability by emitting particles / radiation.

42
Q

Define Half Life (t 1/2).

A

The time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value.

43
Q

Describe the process of alpha decay.

A
  • Emission of an alpha particle
  • Helium nuclei
  • Positively charged
44
Q

Describe the process of beta decay.

A

2 types:

  • Beta Minus: Emission of an electron
  • Beta Plus: Emission of a positron (anti-electron)
45
Q

Describe the process of gamma decay.

A
  • Emission of a gamma photon
  • High frequency EM radiation
  • Neutral
  • No effect on atomic / mass number
  • Often produced along with alpha / beta particles: alpha / beta decay leaves nucleus in an excited state; it then loses energy by gamma emission
46
Q

Describe the penetrating power of alpha, beta and gamma.

A
  • Alpha: Stopped by paper
  • Beta: Stopped by aluminium sheets
  • Gamma: Stopped by block of lead
47
Q

What is the use of Xofigo (Radium Ra233 Dichloride)?

A

Used to treat metastatic prostate cancer patients - have a localised effect

48
Q

Describe the industrial applications of unstable isotopes.

A
  • Energy generation
  • Sterilisation of food and medical supplies (usually uses Cobalt-60)
  • Imaging and gauging
49
Q

Describe the domestic applications of unstable isotopes.

A
  • Smoke detectors (using 241-Am)
50
Q

Describe the medical applications of unstable isotopes.

A
  • Diagnostic

- Therapeutic (weakening / destroying particular targeted cells)

51
Q

Describe the requirements of unstable isotopes for imaging.

A
  • Short half-life so it decays away soon after imaging is complete
  • Radioisotope used for diagnosis must emit gamma rays of sufficient energy to escape from the body
  • Must have a half-life short enough for it to decay away soon after imaging is complete
52
Q

What unstable isotope is typically used for imaging?

A
  • 99 Tc-m
  • t 1/2 = 6 hours
  • Emits gamma and low energy beta particles
  • Produced on site in a generator
53
Q

What is Myocardial Perfusion Imaging (MPI) used for?

A

Detection and prognosis of coronary artery disease

54
Q

What unstable isotopes are used for Myocardial Perfusion Imaging (MPI)?

A
  • 201 TiCl
  • 82 Rb
  • 99 Tc-m
55
Q

What does Proton Emission Tomography (PET) imaging often use?

A
  • 18 F Fluoro-deoxy Glucose (FDG)
  • t 1/2 = 110 minutes
  • Measures cell metabolism
56
Q

What are other 18 F compounds used for?

A

Imaging DNA synthesis and hypoxia

57
Q

Describe the requirements of unstable isotopes for imaging.

A
  • Selective damage to unhealthy tissue
  • Radioisotope used should be a strong beta emitter to damage cells in small area
  • Gamma emission allows imaging as well
  • Can be implanted near tumour (Brachytherapy)
  • Or is injected with selective uptake
58
Q

Describe the uses of radioiodine.

A
  • 132 I for diagnostics
  • 131 I for treatment of overactive thyroid / thyroid cancer
  • t 1/2 = 8.02 days
  • Decays by beta and gamma emission
59
Q

What unstable isotopes are used to treat bone metastasis?

A
  • 89 SrCl
  • 153 Sm
  • t 1/2 = 1.93 days
  • Beta emission
60
Q

What unstable isotope is used in the control of red blood cell production in the bone marrow, in polycythaemia vera?

A
  • 32 P
  • t 1/2 = 14.28 days
  • Beta emission
61
Q

Describe the uses of Lutetium-177 and Yttrium-90.

A

Multiple uses; conjugated to peptides / antibodies

e.g. Zevalin, in sealed source brachytherapy

CLS3003-B: Chemistry (Semester 1) (13 decks)

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