Radioactivity dating to materials I want to be naked in a chat room
After one half-life, a 1.00 gram sample of uranium will have decayed to 0.50 grams of \(\ce\)-238 and 0.43 grams of \(\ce\)-206.
Although chemical changes were sped up or slowed down by changing factors such as temperature, concentration, etc, these factors have no effect on half-life.
The boat of a pharaoh was discovered in a sealed crypt and reassembled in a museum near the pyramids (see Fig. The age of our galaxy and earth also can be estimated using radioactive dating.
Using the decays of uranium and thorium, our galaxy has been found to be between 10 and 20 billion years old and the earth has been found to be 4.6 billion years old. Within experimental error, this estimate agrees with the 15 billion year estimate of the age of the Universe.
How long did it take for half of our isotope to change?
It took approximately 200 years for \(100\%\) of our sample to leave only \(50\%\) (half of the original amount) remaining. *Notice that after another 200 years (400 years total), \(25\%\) remains (half of \(50\%\)) Look carefully at the graph in the previous example.
The quantity of radioactive nuclei at any given time will decrease to half as much in one half-life.