An atom with the same number of protons in the nucleus but a different number of neutrons is called an isotope.For example, uranium-238 is an isotope of uranium-235, because it has 3 more neutrons in the nucleus.
When looking at a large number of atoms, you see that a certain fraction of them will change or dating system because you can determine accurate ages from the number of remaining radioactive atoms in a rock sample.
radiation sickness,harmful effect produced on body tissues by exposure to radioactive substances.
The biological action of radiation is not fully understood, but it is believed that a disturbance in cellular activity results from the chemical changes caused by ionization (see.....
However, the crater number relation must be calibrated against something with a known age.
To measure the passage of long periods of time, scientists take advantage of a regularity in certain unstable atoms.