Alpha particle facts for kids
An alpha particle is a tiny, fast-moving particle. It is made up of two protons and two neutrons. Think of it like the center part (the nucleus) of a helium atom, but without any electrons.
Radioactive elements release alpha particles when they go through a special process called alpha decay. This is how unstable atoms change into more stable ones.
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How Alpha Decay Works
During alpha decay, an atom's atomic nucleus lets go of an alpha particle. When this happens, the nucleus loses two protons and two neutrons. Because the atom loses two protons, it actually changes into a completely different element!
For example, when americium goes through alpha decay, it changes into neptunium. This is because neptunium has exactly two fewer protons than americium. Alpha decay usually happens in very heavy elements. These are elements that have many protons and neutrons, like uranium, thorium, plutonium, and radium.
Are Alpha Particles Dangerous?
Alpha particles cannot travel very far. They can't even go through a few centimeters of air! This means alpha radiation usually can't hurt humans if the source is outside the body. Our skin is thick enough to block alpha particles. They simply cannot penetrate it.
However, alpha radiation can be very harmful if the source gets inside the body. This can happen if people breathe in dust or gas that contains materials giving off alpha particles.
Let's look at americium again. The type called americium-241 gives off alpha radiation. If this radiation gets inside someone's body, it can be very dangerous. It can damage the DNA inside our cells. But remember, it's not harmful when it's outside the body because alpha radiation doesn't travel through the outer layers of skin very well.
Who Discovered Alpha Particles?
When scientists write equations about nuclear reactions, they use the Greek letter Alpha. This tradition started with Ernest Rutherford. He was a famous scientist who discovered and named three main kinds of ionizing radiation: alpha, beta, and gamma.
Images for kids
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A physicist observes alpha particles from the decay of a polonium source in a cloud chamber.
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Alpha radiation detected in an isopropanol cloud chamber (after injection of an artificial source radon-220).
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Dispersing of alpha particles on a thin metal sheet.
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Energy-loss (Bragg curve) in air for a typical alpha particle emitted through radioactive decay.
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The trace of a single alpha particle obtained by nuclear physicist Wolfhart Willimczik with his spark chamber specially made for alpha particles.
See also
In Spanish: Partícula alfa para niños
