half life
Time it takes for half of an isotope to decay
isotopes
Atoms of the same element having different masses because they contain different numbers of neutrons.
radioactive decay
A spontaneous process in which unstable nuclei lose energy by emitting radiation
parent element
The original element before it turns into another element through decay.
daughter element
the new element that results from the radioactive decay of the parent element
88
Approximately what percentage of daughter material is present when the third half life is reached.
15
Ac-228 has a half life of 6.13 hours. Approximately how many mg of a 240.0 mg sample would remain after one day? (Hint: round 6.13 to the nearest whole number)
50
The half life of Uranium-238 is 4.5 billion years and the age of earth is 4.5 billion years. What percent of Uranium-238 that was present when Earth was formed still remains?
75
The half life of iodine-125 is 60 days. If the initially sample is 4800 mg, how many mg of iodine-125 would be left after 360 days?
30
If 20.0 g of a radioactive isotope are present at 1:00 PM and 5.0 g remain at 2:00 PM, how many minutes is the half life of the isotope?
32
The half life of radium 226 is 1602 years. If you have 500 grams of radium today how many kilograms would have been present 9612 years ago?