The half-life of a radioactive nuclide is defined as the time it takes half of a sample of the element to decay.

A mathematical formula can be used to calculate the half-life from the number of breakdowns per second in a sample of the nuclide.

Some nuclides have very long half-lives, measured in billions or even trillions of years.

radioactive dating of rock samples is a method of-50radioactive dating of rock samples is a method of-13radioactive dating of rock samples is a method of-49

The man's body was recovered and pieces of tissue were studied for their C content by accelerator mass spectroscopy.

The best estimate from this dating technique says the man lived between 33 BC. From the ratio, the time since the formation of the rock can be calculated.

Radiometric dating methods are the strongest direct evidence that geologists have for the age of the Earth.

All these methods point to Earth being very, very old -- several billions of years old.

The mass number doesnt change, while the atomic number goes down by 1.

So an atom of potassium-40 (K40), atomic number 19 can absorb an electron to become an atom of argon-40 (Ar40), atomic number 18.

I found several good sources, but none that seemed both complete enough to stand alone and simple enough for a What is radiometric dating?

Simply stated, radiometric dating is a way of determining the age of a sample of material using the decay rates of radio-active nuclides to provide a 'clock.' It relies on three basic rules, plus a couple of critical assumptions.

Uranium-238 contains 92 protons and 146 neutrons, while uranium-235 contains 92 protons and 143 neutrons.

To keep it short, a nuclide is usually written using the elements abbreviation.

C and counting the amount of each) allows one to date the death of the once-living things.