To read the time on this radioactive clock, scientists use a device called a mass spectrometer to measure the number of parent and daughter atoms.The ratio of parents to daughters can tell the researcher how old the specimen is.An investigation into the disaster later revealed that the true death count was impossible to know because so many bodies had in effect been cremated in the intense blaze. Hiram Rhoades Revels, a Republican from Natchez, Mississippi, is sworn into the U. Senate, becoming the first African American ever to sit in Congress. The Passion of the Christ, Mel Gibson’s film about the last 44 hours of Jesus of Nazareth’s life, opens in theaters across the United States on this day in 2004.
On this day in 1779, Fort Sackville is surrendered, marking the beginning of the end of British domination in America’s western frontier.
Usually, atoms have an equal number of protons and neutrons.
If there are too many or too few neutrons, the atom is unstable, and it sheds particles until its nucleus reaches a stable state.
The more parent isotopes there are -- and the fewer daughter isotopes -- the younger the sample.
The half-life of the isotope being measured determines how useful it is at dating very old samples.
Radiometric dating relies on the properties of isotopes.