Radioactivity Part 1 Flashcards
When was radioactivity discovered?
March 1, 1896
Who discovered radioactivity?
Antoine Henri Becquerel
French physicist who accidentally discovered radioactivity by opening a drawer
Antoine Henri Becquerel
When was Antoine Becquerel born?
In Paris, 1852
What did Antoine studied because of his father?
Fluorescence and Phosphorescence
Becquerel was specially interested in what?
Uranium and its compounds
Who is Antoine Henri Becquerel’s father?
Edmond Becquerel
This is where Becquerel first heard about Roentgen’s theory.
French Academy of Sciences
TRUE or FALSE: From Becquerel’s accidental discovery, uranium salts emitted radiation without any stimulation from sunlight.
True
TRUE or FALSE: It was announced that Uranium was indeed what was emitting the radiation.
True
They began studying the strange Uranium rays
Marie Sklodowska Curie and Pierre Curie
When did the Curies started studying the strange Uranium rays?
1898
What are the 3 radioactive elements discovered by the Curies?
- Polonium (Po)
- Thorium (Th)
- Radium (Ra)
What did the Curies mainly discovered?
They figured out how to measure the intensity of radioactivity
Who coined the term “radioactivity”
Marie Curie
Becquerel and the Curies shared what specific award, for their work in radioactivity?
1903 Nobel Prize
This is a naturally-occurring phenomenon in a number of substances
Radioactivity
This is where atoms of a substance spontaneously/continuously emit invisible but energetic radiations, which can penetrate materials that are opaque to visible light
Radioactivity
Radioactivity can be harmful to living cells but can be helpful to the field of what?
Field of medicine
TRUE or FALSE: Vast majority of nuclei found on Earth is not stable.
False, because most of nuclei found on Earth is indeed, stable.
Approximate number of stable isotopes:
270 stable isotopes
Number of naturally-occurring radioisotopes:
50 radioactive isotopes (radioisotopes)
This is a plot of nuclei as a function of proton/atomic number (z) and neutron number (N) which includes all stable nuclei and known radioactive nuclei, either man-made or natural, along with their decay properties
Chart of nuclides
TRUE or FALSE: Nuclei are unstable if they are excited, that is, not in their lowest energy states.
True
“Nature seeks the lowest energy state”
Nuclear stability
TRUE or FALSE: Things are most stable in their lowest energy state, while unstable atoms will try and become stable by getting to a lower energy state by emitting some form of radioactivity
True
What are the 3 forces that works in the nucleus in holding or not holding protons?
- Electromagnetic forces
- Strong force
- Weak force
A type of force wherein it follows the principle of like charges repel ; positive charges of protons tend to force the protons apart
Electromagnetic force
This type of force counters EM force ; attracts protons to each other
Strong force
This force governs how an unstable nucleus will decay into a stable nucleus
Weak force
This is a successful way in predicting nuclear stability
Neutron-to-proton ratio (n/p)
TRUE or FALSE: N/P ratio is close to 1 for atoms of elements with low atomic numbers (less than 20 protons)
True
TRUE or FALSE: element 84 and beyond is unstable.
True
TRUE or FALSE: N/P ratio increases as the atomic number increases past element 20 (Calcium) to 84 (Polonium)
True
This particle of an atom helps in binding the nucleus together
Neutrons
Whether a nucleus contains an odd/even number of protons and neutrons
Predicting Nuclear Stability
Choose from the two choices in the parenthesis:
Nuclides containing odd numbers of both protons and neutrons are (more , less) stable and more radioactive.
Less
TRUE or FALSE: Nuclides containing even numbers of both protons and neutrons are most stable.
True
TRUE or FALSE: Greater binding energy means a more stable nucleus.
True
This is a plot of the number of neutrons vs the number of protons for stable nuclei reveals that the stable isotopes fall into a narrow band.
Belt of Stability or Band of Stability
This is a property exhibited by certain types of matter emitting energy and subatomic particles spontaneously
Radioactivity
TRUE or FALSE: Unstable nucleus will decompose spontaneously, or decay, into a more stable configuration.
True
What are the 2 main sources of radioactivity?
- Natural environmental sources
- Artificial sources
This originates in outer space continuously bombarded the Earth’s gaseous envelope
Cosmic rays
These include long-lived radioactive elements such as uranium, thorium, and any of their decay product, such as radium and radon.
Terrestrial sources
These are products of nuclear reaction initiated by man
Artificial sources
These are designed to produce power, neutrons, radioisotopes, and fissile materials
Nuclear reactors
This is the primary source of radiation from the human body
Potassium-40 (40K)
2 reasons why potassium is the primary source of radiation from the human body:
- Present in all the tissues in the body
- Easy to digest
This is the number of times a radioactive decay occurs in the sample per unit time
Activity (decay rate)
TRUE or FALSE: Activity of a radioactive sample decreases with time
True
1 Bq = ? dps
1 dps
1 Ci = ? dps
3.7 x 10^10 dps
1 Ci = ? Bq
3.7 x 10^10 Bq
1 Bq = ? Ci
2.7 x 10^-11 Ci
1 mci = ? Ci
0.0001 Ci or 1x10^-3 Ci
1 μci = ? Ci
0.000001 Ci or 1x10^-6 Ci
This is the activity per unit mass of a substance, whether atoms of a single nuclide or a compound
Specific activity
unit of specific activity:
Bq/kg (SI unit), Ci/g, or dpm/g
This is the amount of time it takes for the decay rate to reach half of its original value
Half-life (t 1/2)
Types of half-life:
- Physical Half-Life
- Biological Half-life
- Effective Half-life
Period of time required to reduce the radioactivity level to a source to exactly one half of its original value.
Physical half-life
This reduces the amount of drug/pharmaceutical in an organ or the body to exactly one half of its original value.
Biological half-life
This reduces the radioactivity level of an internal organ or the whole body to exactly one half of its original value.
Effective half-life