Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes.Learn about half-life and how it is used in different dating methods, such as uranium-lead dating and radiocarbon dating, in this video lesson. As we age, our hair turns gray, our skin wrinkles and our gait slows.If two reactions have the same order, the faster reaction will have a shorter half-life, and the slower reaction will have a longer half-life.The half-life of a first-order reaction under a given set of reaction conditions is a constant.The units of measure for time are dependent upon the unit of measure for the rate constant.The ratio of "N/N Carbon-14 is a radioisotope formed in our atmosphere by the bombardment of nitrogen-14 by cosmic rays.In this equation, the units of measure for N and No can be in grams, atoms, or moles.

The electric force between the nucleus and electrons holds the atom together.

, where r is a measurement of the rate of decay, k is the first order rate constant for the isotope, and N is the amount of radioisotope at the moment when the rate is measured.

The rate of decay is often referred to as the activity of the isotope and is often measured in Curies (Ci), one curie = 3.700 x 10" is the initial amount of radioisotope at the beginning of the period, and "k" is the rate constant for the radioisotope being studied.

The amount of carbon-14 in the atomosphere is, on an average, relatively constant.

Plants take in carbon-14 through the process of photosynthesis.

This becomes evident when we rearrange the integrated rate law for a first-order reaction (Equation 14.21) to produce the following equation: Figure \(\Page Index\): The Half-Life of a First-Order Reaction.

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