Uranium-238

What is Uranium-238?

Uranium-238 is a special kind of uranium found in nature. It makes up more than 99% of all uranium on Earth. Scientists write it as ²³⁸U or U-238.

Unlike another kind called uranium-235, U-238 does not easily create a chain reaction in normal reactors. But it can change into something useful when hit by fast-moving particles. This change creates a material called plutonium-239, which is important for energy.

How Old is Uranium-238?

Uranium-238 changes very slowly over time. It takes about 4.463 billion years to change into another element. Because it changes so slowly, we still find lots of it today.

U-238 helps make about 40% of the heat inside our planet. As it changes, it gives off tiny particles that scientists can study to learn more about Earth.

Uses of Uranium-238

Scientists use U-238 to study very old rocks and materials. They call this method radiometric dating. It helps them find the age of some of the oldest rocks on Earth.

Uranium-238 can also help make energy. In special reactors, it can change into plutonium-239, which gives us more fuel for power.

U-238 is also used to block harmful invisible rays, keeping things safe. It is very good at protecting against many types of radiation.

How Uranium-238 Changes

Uranium-238 changes slowly into other elements over a very long time. It starts by turning into thorium-234. Thorium-234 then changes in steps, becoming many different elements. This slow change is called the radium series or uranium series.

Eventually, after many steps, U-238 changes into a stable form of lead. Each step takes its own time, and the whole process can take billions of years.

Scientists use these changes to find the age of very old things, like rocks and even the Earth itself.