radioactivity and nuclear reactions Flashcards
What is radioactivity?
The breakdown of the unstable nucleus of an atom.
What does a radioactive atom decay to produce?
An atom with fewer neutrons/protons (a lighter atom)
What is a radioisotope?
The unstable and radioactive isotope of an element
What is the half life of an isotope?
The time it takes for one half of the nuclei in a same to undergo radioactive decay.
How much of an original sample will remain after one half life?
50%
How much of an original sample will remain after 2 half lives?
25%
How is polonium mainly used?
As a source of neutrons, generally by combining with beryllium
How many known isotopes does polonium have?
Over 25
What is polonium’s most common isotope, and what is it’s half life? What does it’s decay produce?
Po-210
138 days
Lead 206 and lots of energy
How is radon produced?
The radioactive decay of Radium
What is radon’s isotope with the longest half life, and how long is it?
radon-222
4 days
radon is a _____ at a normal room temp
colorless radioactive gas
What are radium’s properties? (4)
Highly reactive, brilliant white, metal, blackens when exposed to air.
What are alpha particles?
Particles that have a nucleus that is the same as helium w/ two protons and two neutrons
What happens when an atom undergoes alpha decay?
The atom loses two of its protos and two of it’s neutrons, which form an alpha particle. Atomic # decreases by two, mass # by 4
How far does alpha radiation travel? What can it (or cannot it) penetrate?
They travel a very short distance by air
Cannot penetrate skin or a thin sheet of paper.
Are alpha particles radioactive? What do they do after losing their energy>
No, they do not decay further.
After losing their energy, they attract to electrons to become helium atoms.
What is beta radiation?
Radiation made of high energy electrons (negative charge) sent out by a radioactive/unstable nuclei
What happens when an atom undergoes beta radiation?
A neutron becomes a proton. The atomic # increases by 1 and the mass stays the same.
How far does beta radiation travel? What can it (or cannot it) penetrate?
Can travel several meters through air but stopped by solid material
Can penetrate human skin but clothing blocks most
What is gamma radiation?
Radiation composed of high energy photons (the smallest unit of electromagnetic radiation) that are emitted by radioactive decay of atomic nuclei. Does not cause the identity of an atom to change.
How far does gamma radiation travel? What can it (or cannot it) penetrate?
Able to travel many meters in air.
Easily penetrates most materials.
Frequently comes with alpha and beta radiation.
What are nuclear reactions?
changes that occur in the structure of the atomic nuclei.
What is energy that results from nuclear reactions called?
Nuclear energy or atomic energy
What is nuclear fission?
Nuclear reaction where nucleus splits into two smaller parts, normally same size. Releases a lot of energy
How is uranium nuclei split?
By bombarding it with neutrons
What is nuclear fusion?
Nuclear reaction where the nuclei of two atoms join to make a bigger nucleus. Energy is given off.
Nuclear fusion occurs under ery ___ conditions
hot
Sun and other stars create energy through ____
nuclear fusion
In the sun, hydrogen nuclei ___ to make helium
fuse
