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

L2 - Atomic Structure & Isotopes Flashcards

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
Describe the uses of carbon-14.
- Radioactive | - Used for radiocarbon dating
26
Name the 2 isotopes of chlorine.
- Chlorine-35 | - Chlorine-37
27
Name the 2 isotopes of bromine.
- Bromine-79 | - Bromine-81
28
Define Relative Atomic Mass (Ar).
(Of an element) is the weighted average of the individual isotopes.
29
How is measured atomic weight / average atomic weight calculated?
(Isotopic Abundance * Isotope Mass Number) / Isotopic Abundance
30
What does ordinary chlorine consist of?
- 3 atoms of Chlorine-35 | - 1 atom of Chlorine-37
31
Describe stable isotopes.
Remain uncharged indefinitely
32
Describe unstable isotopes.
- 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
Both forms of isotopes can be used as __________ _____ and _______.
- Diagnostic Tools | - Tracers
34
How does mass spectrometry work?
Measures the molecular weight of atoms or compounds by observing the mass to charge ratio (m/z) of ions.
35
State the applications of mass spectrometry.
- Determining isotopic abundances | - Identity of small molecules and proteins
36
Upon which principle is mass spectrometry based?
Atoms and molecules are converted into ions, which can be separated on the basis of their masses and motions in magnetic / electrical fields.
37
What does the position of peaks on a mass spectrum tell us?
Atomic Mass
38
What does peak intensity on a mass spectrum tell us?
Relative Abundance
39
Describe how abundance on a mass spectrum is presented.
Usually highest abundance is scaled up to 100% - other values are adjusted accordingly.
40
Many stable isotopes are used in __________ ________.
Biomedical research
41
Describe what happens during radioactive decay.
The nucleus of an unstable radioisotope seeks energetic stability by emitting particles / radiation.
42
Define Half Life (t 1/2).
The time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value.
43
Describe the process of alpha decay.
- Emission of an alpha particle - Helium nuclei - Positively charged
44
Describe the process of beta decay.
2 types: - Beta Minus: Emission of an electron - Beta Plus: Emission of a positron (anti-electron)
45
Describe the process of gamma decay.
- 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
Describe the penetrating power of alpha, beta and gamma.
- Alpha: Stopped by paper - Beta: Stopped by aluminium sheets - Gamma: Stopped by block of lead
47
What is the use of Xofigo (Radium Ra233 Dichloride)?
Used to treat metastatic prostate cancer patients - have a localised effect
48
Describe the industrial applications of unstable isotopes.
- Energy generation - Sterilisation of food and medical supplies (usually uses Cobalt-60) - Imaging and gauging
49
Describe the domestic applications of unstable isotopes.
- Smoke detectors (using 241-Am)
50
Describe the medical applications of unstable isotopes.
- Diagnostic | - Therapeutic (weakening / destroying particular targeted cells)
51
Describe the requirements of unstable isotopes for imaging.
- 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
What unstable isotope is typically used for imaging?
- 99 Tc-m - t 1/2 = 6 hours - Emits gamma and low energy beta particles - Produced on site in a generator
53
What is Myocardial Perfusion Imaging (MPI) used for?
Detection and prognosis of coronary artery disease
54
What unstable isotopes are used for Myocardial Perfusion Imaging (MPI)?
- 201 TiCl - 82 Rb - 99 Tc-m
55
What does Proton Emission Tomography (PET) imaging often use?
- 18 F Fluoro-deoxy Glucose (FDG) - t 1/2 = 110 minutes - Measures cell metabolism
56
What are other 18 F compounds used for?
Imaging DNA synthesis and hypoxia
57
Describe the requirements of unstable isotopes for imaging.
- 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
Describe the uses of radioiodine.
- 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
What unstable isotopes are used to treat bone metastasis?
- 89 SrCl - 153 Sm - t 1/2 = 1.93 days - Beta emission
60
What unstable isotope is used in the control of red blood cell production in the bone marrow, in polycythaemia vera?
- 32 P - t 1/2 = 14.28 days - Beta emission
61
Describe the uses of Lutetium-177 and Yttrium-90.
Multiple uses; conjugated to peptides / antibodies e.g. Zevalin, in sealed source brachytherapy

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

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