Describe how radioactive dating works

The bone was 68 million years old, and conventional wisdom about fossilization is that all soft tissue, from blood to brains, decomposes.Only hard parts, like bones and teeth, can become fossils.These are chemical elements, like carbon or uranium, that are identical except for one key feature -- the number of neutrons in their nucleus.Usually, atoms have an equal number of protons and neutrons.The half-life of the isotope being measured determines how useful it is at dating very old samples.Once all the parents have become daughters, there's no more basis for comparison between the two isotopes.If you try to add extra blocks to the sides pyramid, they may stay put for a while, but they'll eventually fall away.

By 1907 study of the decay products of uranium (lead and intermediate radioactive elements that decay to lead) demonstrated to B. Boltwood that the lead/uranium ratio in uranium minerals increased with geologic age and might provide a geological dating tool.

The element's half-life is the amount of time it takes for half the parent atoms in a sample to become daughters.

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 number of parent atoms originally present is simply the number present now plus the number of daughter atoms formed by the decay, both of which are quantities that can be measured.

Samples for dating are selected carefully to avoid those that are altered, contaminated, or disturbed by later heating or chemical events.

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