L2: The Structure of the Atom

Question 1

What are nucleons?

Answer 1

Protons and neutrons

Question 2

True or false: nucleons determine the properties of an atom

Answer 2

False. Electrons determine the properties of an atom

Question 3

Define an isotope

Answer 3

Atoms with the same atomic number but different mass number (i.e. same number of protons but different numbers of neutrons)

Question 4

True or false: Isotopes have identical chemical properties

Answer 4

True, because the outer shell electron configuration is the same

Question 5

True or false: Isotopes share identical physical properties

Answer 5

False, physical properties, like density, may differ between isotopes

Question 6

What are the three isotopes of hydrogen? What particles are found in each nucleus?

Answer 6

1) Protium (1 proton, 0 neutrons)
2) Deuterium (1 proton, 1 neutron)
3) Tritium (1 proton, 2 neutrons)

Question 7

Which is the most abundant isotope of H?

A) Protium
B) Deuterium
C) Tritium

Answer 7

A) Protium

Question 8

Which isotope of H is most useful for NMR spectroscopy?

A) Protium
B) Deuterium
C) Tritium

Answer 8

B) Deuterium

Question 9

Which isotope of H is radioactive?

Answer 9

C) Tritium

Question 10

How many protons are found in each H nucleus?

Answer 10

1

Question 11

What is the fate of a stable isotope?

Answer 11

Remains unchanged indefinitely

Question 12

What is the fate of an unstable isotope?

Answer 12

Spontaneously disintegrate to become stable.

Question 13

What happens when an unstable isotope disintegrates?

Answer 13

Small particles and/or radiation are emitted

Question 14

Which type of isotope (stable or unstable) are useful as diagnostic tools and tracers in scientific research?

Answer 14

Both!

Question 15

What method is most commonly used to detect isotopes?

Answer 15

Mass spectrometry

Question 16

True or false: Mass spectrometry can be used to detect relative abundance of isotopes

Answer 16

True

Question 17

True or false: Mass spectrometry can determine the identity of small particles and proteins

Answer 17

True

Question 18

What must atoms and molecules be converted to before the mass spectrometer can analyse their composition?

Answer 18

Ions - this allows them to be separated based on their masses and motions in magnetic or electrical fields

Question 19

True or false: In mass spectrometry, the position of the peak gives the relative abundance?

Answer 19

False. The relative abundance is given by the intensity of the peak

Question 20

True or false: In mass spectrometry, the position of the peak gives the atomic mass

Answer 20

True

Question 21

What are the three types of radiation that can be emitted by radioactive isotopes?

Answer 21

1) Alpha particle
2) Beta particle
3) Gamma photon

Question 22

True or false: an alpha particle is equivalent to a hydrogen nucleus

Answer 22

False. It is equivalent to a helium nucleus (2 protons, 2 neutrons)

Question 23

True or false: an alpha particle is uncharged

Answer 23

False. It is positively charged due to the lack of negative particles

Question 24

What are the two types of beta radiation?

Answer 24

1) Beta minus

2) Beta plus

Question 25

What happens in beta plus radiation?

Answer 25

A positron is emitted

Question 26

What happens in beta minus radiation?

Answer 26

An electron is emitted

Question 27

What is emitted in gamma radiation?

Answer 27

A photon

Question 28

True or false: A gamma photon is neutrally charged

Answer 28

True

Question 29

How does gamma radiation effect atomic mass?

Answer 29

It has no effect

Question 30

True or false: Gamma radiation is usually in conjuction with alpha or beta radiation

Answer 30

True. An alpha or beta particle leaves the nucleus in an excited state; it then loses energy by emitting a gamma photon

Question 31

You notice an isotope goes from an atomic mass of 223 to an atomic mass of 219. What type of radiation is in effect?

Answer 31

Alpha - an alpha particle of 2 protons and 2 neutrons has been emitted

Question 32

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?

Answer 32

Alpha - it is stopped by paper; beta and gamma are not

Question 33

What material would make a suitable container for gamma radioactive material?

Answer 33

Lead, as it absorbs gamma radiation

Question 34

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?

Answer 34

It must be gamma as alpha and beta would be absorbed by the aluminium box

Question 35

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?

Answer 35

Either beta or gamma. Both would pass through the paper bag; alpha would not.

Question 36

Give four industrial uses of unstable isotopes

Answer 36

1) Energy generation 2) Sterilisation of food and medical supplies 3) Smoke detectors 4) Imaging and gauging

Question 37

Give two medical uses of unstable isotopes

Answer 37

1) Provide diagnostic information | 2) Treatment by targeting cells

Question 38

Which radioisotope is most commonly used in imaging? Why?

Answer 38

Technitium. - Emits gamma ray and low energy beta - Half life of 6 hours - Can be produced on sit

Question 39

What are the requirements of any radioisotope that is to be used in imaging?

Answer 39

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

Question 40

What imaging method may use thallium-201 chloride, Rb-82, or Tc-99? What is used for?

Answer 40

Myocardial Perfusion Imaging (MPI). Detection and prognosis of coronary artery disease

Question 41

Which radioisotope is used in PET imaging to measure cell metabolism? Why?

Answer 41

18F-Fluoro-deoxy glucose. Half life of 110 minutes.

Question 42

What are the uses of radioiodine? (2 isotopes)

Answer 42

Iodine-132 is used in diagnostics Iodine-131 is used to treat hyperthyroid or thyroid cancer

Question 43

What is the half life and radiation-type of Iodine-131?

Answer 43

8.02 days | Beta and gamma radiation

Question 44

What type of radiation is best suited to radiotherapy?

Answer 44

Strong beta to damage cells in a small, controlled area

Question 45

What are Sr-89 Chloride and Sm-153 used for in radiotherapy?

Answer 45

Bone metastasis

Question 46

What is P-32 used for in radiotherapy?

Answer 46

Polycythaemia. P-32 beta emissions control the production of red blood cells in bone marrow

Question 47

What is the half life of P-32?

Answer 47

14.28 days

Question 48

Lutetium-177 and Yttrium-90 are commonly used how?

Answer 48

Conjugated to peptides or antibodies in radiotherapy