Helium-4 facts for kids
Helium-4 (also written as 4He) is a special type of helium atom. It's the most common kind of helium found in the universe. On Earth, almost all helium (99.99986%) is helium-4. The center of a helium-4 atom is called its nucleus. This nucleus is also known as an alpha particle. Each helium-4 atom has 2 protons (tiny parts with a positive charge), 2 neutrons (tiny parts with no charge), and 2 electrons (tiny parts with a negative charge that orbit the nucleus).
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Where Helium-4 Comes From
Helium-4 is made in different ways, both on Earth and in space.
How it's Made in Space
Most of the helium-4 in the universe was created during the Big Bang. This was the huge event that started the universe. This "Big Bang helium-4" is often called "primordial helium."
Helium-4 is also made inside stars, like our Sun. This happens through a process called nuclear fusion. In fusion, lighter atoms combine to form heavier ones, releasing a lot of energy.
How it's Made on Earth
On Earth, helium-4 is mostly made from radioactive decay. This is when heavy elements, like uranium or thorium, slowly break down. When they break down, they release tiny particles, including alpha particles (which are helium-4 nuclei). This process happens deep inside the Earth's crust.
The "primordial helium" from the Big Bang is not found on Earth. This is because it escaped into space when Earth was first forming and was extremely hot.
Helium-4 in the Universe
Helium-4 is very common in the universe. About one-quarter (25%) of all the mass in the universe is helium-4. The rest is mostly hydrogen.
Superfluid Helium-4
When liquid helium-4 is cooled down to a very low temperature, below -271.17 °C (which is 2.71 K), something amazing happens. It turns into a superfluid.
What is a Superfluid?
A superfluid is a very special kind of fluid. It has properties that are very different from normal liquids like water or oil. For example, a superfluid has no friction at all. This means it can flow forever without losing energy.
If you put superfluid helium-4 in an open container, it won't just sit there. It will actually climb up the walls of the container and spill out! This strange behavior is called a "Rollin film." It happens because of special rules in quantum mechanics, which is the science of very tiny particles.
Why Helium-4 Becomes a Superfluid
The nucleus of a helium-4 atom has a total spin of zero. This makes it a type of particle called a boson. Superfluid behavior is a form of something called a Bose–Einstein condensate. This special state of matter can only be achieved by bosons when they are cooled to extremely low temperatures.
Where Else is Helium-4 Found?
Besides Earth and space, helium-4 can also be found on the Moon. Scientists are interested in it because it could be a future energy source.
See also
In Spanish: Helio-4 para niños
