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Elements for Kids

Helium

The element helium

  • Symbol: He
  • Atomic Number: 2
  • Atomic Weight: 4.00260
  • Classification: A noble gas and a nonmetal
  • Phase at Room Temperature: Gas
  • Density: 0.1786 g/L @ 0°C
  • Melting Point: -272.20°C, -457.96°F
  • Boiling Point: -268.93°C, -452.07°F
  • Discovered by: Pierre Janssen in 1868


Helium is the second lightest and second most common element in the universe. It is at the top of the noble gas group in the periodic table.

Characteristics and Properties

At room temperature helium is an odorless, tasteless, colorless gas. It has very low boiling and melting points, meaning that it is generally found in the gas phase except under the most extreme of conditions. Helium is the only element that does not solidify under ordinary pressures and remains a liquid even at absolute zero.

Helium is one of the inert or noble gases. This means that its outside electron shell is filled with electrons. This makes it very unreactive and non-flammable.

Where is helium found on Earth?

Helium is fairly rare on Earth. There is very little in the Earth's atmosphere because it is so light that it eventually escapes into outer space.

Scientists believe that most of the helium in the universe was created at the formation of the universe. However, new helium is created in the center of stars and also as part of radioactive decay on Earth. Helium from radioactive decay can be found trapped underground in natural gas reservoirs.

Stars

Helium is constantly being produced at the internal cores of stars. Deep inside a star, intense pressures cause hydrogen atoms to convert into helium atoms. This creates the energy, heat, and light that powers the stars and the sun. This conversion is called nuclear fusion.

How is helium used today?

Helium is used in balloons and airships to make them float. It is not as light at hydrogen, but is a much safer gas as hydrogen is very flammable.

The largest industrial user of helium gas is MRI scanners which use the gas to keep the superconducting magnets cool. Other applications include silicon wafers for electronics and as a protective gas for arc welding.

How was it discovered?

Helium was first discovered in 1868 by astronomer Pierre Janssen. He noticed the new element when studying a solar eclipse. The element wasn't found on Earth until 1895.

Where did helium get its name?

Helium gets its name from the Greek word "helios" meaning "sun". Helios is also the name of the Greek god of the Sun.

Isotopes

There are eight known isotopes of helium. The most abundant of the helium isotopes is Helium-4 which was largely created at the beginning of the universe.

Interesting Facts about Helium


More on the Elements and the Periodic Table

Elements
Periodic Table

Alkali Metals
Lithium
Sodium
Potassium

Alkaline Earth Metals
Beryllium
Magnesium
Calcium
Radium

Transition Metals
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Silver
Platinum
Gold
Mercury
 Post-transition Metals
Aluminum
Gallium
Tin
Lead

Metalloids
Boron
Silicon
Germanium
Arsenic

Nonmetals
Hydrogen
Carbon
Nitrogen
Oxygen
Phosphorus
Sulfur
 Halogens
Fluorine
Chlorine
Iodine

Noble Gases
Helium
Neon
Argon

Lanthanides and Actinides
Uranium
Plutonium

More Chemistry Subjects

Matter
Atom
Molecules
Isotopes
Solids, Liquids, Gases
Melting and Boiling
Chemical Bonding
Chemical Reactions
Radioactivity and Radiation
 Mixtures and Compounds
Naming Compounds
Mixtures
Separating Mixtures
Solutions
Acids and Bases
Crystals
Metals
Salts and Soaps
Water
 Other
Glossary and Terms
Chemistry Lab Equipment
Organic Chemistry
Famous Chemists


Science >> Chemistry for Kids >> Periodic Table


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