Uranium, a radioactive metal, eventually decays into lead.
The Earth's crust is a treasure trove of basic chemical elements from actinium to zirconium. You can find uranium ore deposits in many parts of the world, though the most productive mines are in Canada, Khazakhstan, and Australia, according to the New Mexico Bureau of Geology and Mineral Resources. Because uranium is naturally radioactive, it slowly transforms into lead via a chain of other elements. Because of this, you'll find lead in all naturally occurring deposits of uranium ore.
Uranium
The heaviest metal in nature, uranium isn't found in pure form but mixed with other elements in mineral ores such as pitchblende, carnotite and tobernite. As it's a long-lived radioactive element occurring with relative abundance, its main use is fuel for nuclear power plants.
Stability
An atom's stability depends on the balancing of forces in its nucleus. The nucleus, the cluster of protons and neutrons inside an atom, becomes out of balance in the heaviest elements, making them unstable. Most elements have both stable and unstable isotopes. Isotopes are atoms related by the same number of protons but having different numbers of neutrons. Uranium, having the largest natural nucleus in the periodic table, has no stable isotopes.
Radioactive Decay
Forces in an unstable nucleus cause it to eject particles from itself as radioactivity. Whenever a nucleus loses protons, it becomes a different element. This process, called radioactive decay, goes through many complex steps, but the result is a lighter, more stable nucleus.
Decay Chain
Uranium undergoes radioactive decay, transforming itself into several other elements before finally becoming lead. The decay of the uranium 238 isotope, so called because of the number of protons and neutrons in its nucleus, zigzags the periodic table, becoming thorium, polonium, uranium 234 and other elements, finally stopping at lead 206. So not only will you find lead in uranium deposits, but you'll also find these other elements as well.
Half-Life
The time it takes for half the amount of a substance to decay is called its half-life. Every radioactive isotope has a characteristic half-life. Some are less than a second, some are millions of years. The half-life of uranium 238 is 4.5 billion years. The half-lives of the other elements going down the decay chain are quick by comparison, so you can consider 4.5 billion years the time it takes for half your uranium to become lead. If you take a uranium sample and find the percentage of lead in it, you can determine its age.
Tags: other elements, billion years, find lead, into lead, number protons, periodic table, protons neutrons
