L2: The Structure of the Atom Flashcards
What are nucleons?
Protons and neutrons
True or false: nucleons determine the properties of an atom
False. Electrons determine the properties of an atom
Define an isotope
Atoms with the same atomic number but different mass number (i.e. same number of protons but different numbers of neutrons)
True or false: Isotopes have identical chemical properties
True, because the outer shell electron configuration is the same
True or false: Isotopes share identical physical properties
False, physical properties, like density, may differ between isotopes
What are the three isotopes of hydrogen? What particles are found in each nucleus?
1) Protium (1 proton, 0 neutrons)
2) Deuterium (1 proton, 1 neutron)
3) Tritium (1 proton, 2 neutrons)
Which is the most abundant isotope of H?
A) Protium
B) Deuterium
C) Tritium
A) Protium
Which isotope of H is most useful for NMR spectroscopy?
A) Protium
B) Deuterium
C) Tritium
B) Deuterium
Which isotope of H is radioactive?
C) Tritium
How many protons are found in each H nucleus?
1
What is the fate of a stable isotope?
Remains unchanged indefinitely
What is the fate of an unstable isotope?
Spontaneously disintegrate to become stable.
What happens when an unstable isotope disintegrates?
Small particles and/or radiation are emitted
Which type of isotope (stable or unstable) are useful as diagnostic tools and tracers in scientific research?
Both!
What method is most commonly used to detect isotopes?
Mass spectrometry
True or false: Mass spectrometry can be used to detect relative abundance of isotopes
True
True or false: Mass spectrometry can determine the identity of small particles and proteins
True
What must atoms and molecules be converted to before the mass spectrometer can analyse their composition?
Ions - this allows them to be separated based on their masses and motions in magnetic or electrical fields
True or false: In mass spectrometry, the position of the peak gives the relative abundance?
False. The relative abundance is given by the intensity of the peak
True or false: In mass spectrometry, the position of the peak gives the atomic mass
True
What are the three types of radiation that can be emitted by radioactive isotopes?
1) Alpha particle
2) Beta particle
3) Gamma photon
True or false: an alpha particle is equivalent to a hydrogen nucleus
False. It is equivalent to a helium nucleus (2 protons, 2 neutrons)
True or false: an alpha particle is uncharged
False. It is positively charged due to the lack of negative particles
What are the two types of beta radiation?
1) Beta minus
2) Beta plus
What happens in beta plus radiation?
A positron is emitted
What happens in beta minus radiation?
An electron is emitted
What is emitted in gamma radiation?
A photon
True or false: A gamma photon is neutrally charged
True
How does gamma radiation effect atomic mass?
It has no effect
True or false: Gamma radiation is usually in conjuction with alpha or beta radiation
True. An alpha or beta particle leaves the nucleus in an excited state; it then loses energy by emitting a gamma photon
You notice an isotope goes from an atomic mass of 223 to an atomic mass of 219. What type of radiation is in effect?
Alpha - an alpha particle of 2 protons and 2 neutrons has been emitted
You place a detector in a paper bag. Nothing happens when you bring a radioactive sample close by. What type of radiation is being emitted?
Alpha - it is stopped by paper; beta and gamma are not
What material would make a suitable container for gamma radioactive material?
Lead, as it absorbs gamma radiation
You place a detector in an aluminium box. It alerts when you bring an unknown radioactive substance nearby. What type of radiation is in effect?
It must be gamma as alpha and beta would be absorbed by the aluminium box
You place a detector in a paper bag. It alerts when you bring an unknown radioactive substance nearby. What type of radiation is in effect?
Either beta or gamma. Both would pass through the paper bag; alpha would not.
Give four industrial uses of unstable isotopes
1) Energy generation
2) Sterilisation of food and medical supplies
3) Smoke detectors
4) Imaging and gauging
Give two medical uses of unstable isotopes
1) Provide diagnostic information
2) Treatment by targeting cells
Which radioisotope is most commonly used in imaging? Why?
Technitium.
- Emits gamma ray and low energy beta
- Half life of 6 hours
- Can be produced on sit
What are the requirements of any radioisotope that is to be used in imaging?
Must emit gamma rays with sufficient energy to leave the body, and must also have a short half life so it will decay away shortly after the imaging has taken place
What imaging method may use thallium-201 chloride, Rb-82, or Tc-99? What is used for?
Myocardial Perfusion Imaging (MPI). Detection and prognosis of coronary artery disease
Which radioisotope is used in PET imaging to measure cell metabolism? Why?
18F-Fluoro-deoxy glucose. Half life of 110 minutes.
What are the uses of radioiodine? (2 isotopes)
Iodine-132 is used in diagnostics
Iodine-131 is used to treat hyperthyroid or thyroid cancer
What is the half life and radiation-type of Iodine-131?
8.02 days
Beta and gamma radiation
What type of radiation is best suited to radiotherapy?
Strong beta to damage cells in a small, controlled area
What are Sr-89 Chloride and Sm-153 used for in radiotherapy?
Bone metastasis
What is P-32 used for in radiotherapy?
Polycythaemia. P-32 beta emissions control the production of red blood cells in bone marrow
What is the half life of P-32?
14.28 days
Lutetium-177 and Yttrium-90 are commonly used how?
Conjugated to peptides or antibodies in radiotherapy
