Carbon, uranium and potassium are just a few examples of elements used in radioactive dating.Each element is made up of atoms, and within each atom is a central particle called a nucleus.This means that after approximately 4.5 billion years, half of an original sample containing this isotope will decay into its decay product, forming the new isotope, Pb 206 (lead 206).If another 4.5 billion years were to pass, then half of the remaining half of uranium-238 would also decay, leaving 25% uranium to 75% lead.The half-life is the amount of time it takes for half of the atoms of a specific isotope to decay.
To illustrate, let's use the isotope uranium-238, which has a half-life of 4.5 billion years.
When an atom varies in the number of neutrons, the variation is called an isotope. During radioactivity, the unstable isotope breaks down and changes into a different substance.
A new, more stable isotope, called the decay or daughter product, takes its place.
If a scientist were to compute this, s/he would say…
two half-lives went by at a rate of 4.5 billion years per half-life; therefore, the sample is approximately 2 times 4.5 billion or 9 billion years old. So you see, Earth scientists are able to use the half-lives of isotopes to date materials back to thousands, millions and even to billions of years old.
Recently, as reported by Science Daily, radiocarbon dating was used to identify a forged painting based upon the concentrations of carbon-14 (detected on the canvas) within the atmosphere at the time that the picture was painted.