an isotope that has an unstable nucleus and undergoes radioactive decay
When isotopes are unstable they emit energy in the form of radiation.
1. When there are too many or too few neutrons to protons the nucleus becomes unstable
2. At some point, the unstable nucleus will undergo a reaction and lose energy by emitting radiation.
3. During decay, an unstable radioisotope of one element transforms into a stable isotope of a different element.
Atoms of the same element that have different numbers of neutrons
(a) Low penetration. Rays are shielded by
paper or clothes
(B) Higher source of
energy. Shielded by Metal
(Y) Highest energy source. Travels the speed of
light. No mass. No charge. Minimally shielded by
metal and concrete
Alpha particle (4/2He) is given off. Nuclide formed has 2 less protons and a mass number 4
Beta particle ( 0-1e) is given off. Neutron splits into a proton and an
electron. Nuclide formed has 1 MORE proton and
the mass number remains the same.
A positron ( 0+1e) is given off. Nuclide formed has 1 LESS proton
and the mass number remains the same.
An electon ( 0 +1e) is grabbed inside an unstable nucleus. Electron combines with a proton to form a neutron. Nuclide formed has 1 LESS proton and the mass number remains the same.
Radiation that does not cause cells to change
Examples: Radiowaves, Visible Light, Microwaves
Radiation that is harmful to cells, bad for you. Causes mutation to occur (especially of DNA)
Examples: Alpha particles, Beta particles, Gamma rays
Band of stability
Containing no radioactive nuclides in a plot of neutrons vs. atomic #. The region within which all stable nuclei are found. Used to predict if an isotope is stable.
Holds the nucleus together, the force that attracts protons and neutrons to one another.
length of time required for half of the radioactive atoms in a sample to decay.
the time required for one half of the atoms of a radioactive substance to decay.
How to determine half life
Calculate initial amount of isotope. Calculate the amount of isotope left over after a certain number of half lives.
Uranium 235 or Plutonium 239 are the only isotopes. When the nuclei of certain isotopes are bombarded with neutrons, they undergo fission, the splitting of a nucleus into smaller fragments. In a chain reaction, some of the neutrons produced react with other fissionable atoms, producing more neutrons which react with still more fissionable atoms.
The splitting of an atomic nucleus to release energy.
Creation of energy by joining the nuclei of two hydrogen atoms to form helium.
What are the nuclear reactions created in an atomic bomb?
Fission. Atomic bombs are devices that start uncontrolled nuclear chain reactions.
What are the nuclear reaction that happen in the sun?
Fusion. Hydrogen nuclei (protons) fuse to make helium nuclei.