Chemistry definition radioactive dating
The half-life is the amount of time it takes for half of the atoms of a specific isotope to decay.
(Remember, isotopes are variations of elements with a different number of neutrons.) The half-life is reliable in dating artifacts because it is not affected by environmental or chemical factors; it does not change.
These are both isotopes of the element carbon present in a constant ratio while an organism is living; however, once an organism dies, the ratio of carbon-14 decreases as the isotope deteriorates.
Radiocarbon dating can only be used to date items back to as far as about 50,000 years old.
Ever wonder how scientists concluded the age of the earth to be about 4.6 billion years old or how geologists determined the ages of caverns, rocks, volcanoes and the Himalayas? Well, scientists are able to answer all of these wondrous questions and more by use of a process called radiometric or radioactive dating.
Radioactive dating enables geologists to record the history of the earth and its events, such as the dinosaur era, within what they call the geologic time scale.
An isotope disintegrates at a constant rate called the half-life --the time it takes for half the atoms of a sample to decay. By counting the number of half-lives and the percentages remaining of parent and daughter isotopes, scientists are able to determine what they call the absolute age of a discovery.
These neutrons can become unstable, and when they do, they release energy and undergo decay. Radioactivity occurs when the nucleus contains an excess amount of neutrons.When a sample is found, scientists measure the amount of the original or parent isotope and compare it to the amount of the decay product formed.They then count the number of half-lives passed and compute the absolute age of the sample.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.
Radioactive dating uses the ratios of isotopes and their specific decay products to determine the ages of rocks, fossils and other substances.