P6 - Radioactive Materials Flashcards
What is an isotope?
An element that has a different number of neutrons than it does usually.
At what point does an atom become unstable/radioactive?
When they have too many protons or neutrons (Stability is based on the ratio of protons to neutrons).
In an unstable atom, the Nuclear Strong Force fails.
Why do unstable atoms release radiation?
Because it results in the atom becoming more stable.
What are the three types of radiation? Name and Compare them.
When does Alpha Particle Decay occur?
When there are too many protons/neutrons.
When does Beta Particle Decay occur?
When there are too many neutrons.
When does Gamma Energy Decay occur?
When the nucleus has surplus energy that needs to be released.
What happens during Alpha Particle Decay?
Two protons (2p+) and two neutrons (2n0) are released, forming a new detached nucleus (See image).
What happens during Beta Particle Decay?
One Electron (e-) is released and a Neutron (n0) changes into a Proton (p+) (See image for how this is expressed).
What happens during Gamma Particle Decay?
Gamma Energy is released, so there is no mass change (See image for how this is expressed).
What is the force that holds the subatomic particles of a nucleus together called?
The Nuclear Strong Force.
What is the most common form of Background Radiation?
Radon gas, released at surface of ground from uranium in rocks and soil. Roughly 50% of all background radiation.
Define half-life.
The half-life is the time it takes for a substance’s radioactivity to halve.
A substance is considered safe when its activity drops to the same as background radiation, which is ________ ________ per year or ________ ________ per minute.
A substance is considered safe when its activity drops to the same as background radiation, which is 3 millisieverts per year or 25 counts per minute.
What are the most dangerous types of radiation within and outside of the body?
Name some uses of Radiation.
Describe what happens during Nuclear Fission.
- A neutron is fired and absorbed by a large and unstable uranium nucleus.
- The nucleus splits into two roughly equal-sized, smaller nuclei. This releases energy and more neutrons.
- This causes a chain reaction, where the neutrons are absorbed by other nuclei and further fission reactions take place.
- A chain reactions occurs when there’s enough fissile material to prevent too many neutrons escaping without being absorbed. This is called critical mass and ensures every reaction triggers at least one further reaction.
Control rods made from boron can absorb neutrons, and prevent the chain reaction from getting out of control.
