helium

American  

[hee-lee-uhm] / ˈhi li əm /

noun

1. an inert, gaseous element present in the sun's atmosphere and in natural gas, and also occurring as a radioactive decomposition product, used as a substitute for flammable gases in dirigible balloons. He; 4.0026; 2; density: 0.1785 grams/liter at 0°C and 760 millimeters pressure.

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helium British  

/ ˈhiːlɪəm /

noun

1. a very light nonflammable colourless odourless element that is an inert gas, occurring in certain natural gases: used in balloons and in cryogenic research. Symbol: He; atomic no: 2; atomic wt: 4.002602; density: 0.1785 kg/m³; at normal pressures it is liquid down to absolute zero; melting pt: below –272.2°C; boiling pt: –268.90°C See also alpha particle

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helium Scientific  

/ hē′lē-əm /

1. A very lightweight, colorless, odorless element in the noble gas group. Helium occurs in natural gas, in radioactive ores, and in small amounts in the atmosphere. It has the lowest boiling point of any substance and is the second most abundant element in the universe. Helium is used to provide lift for balloons and blimps and to create artificial air that will not react chemically. Atomic number 2; atomic weight 4.0026; boiling point −268.9°C; density at 0°C 0.1785 gram per liter.

2. See Periodic Table

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helium Cultural  

1. A chemical element, usually found in the form of a gas, in which two electrons are in orbit, and the nucleus consists of two protons and two neutrons. Its symbol is He.

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Word History

The second most abundant element in the universe after hydrogen, Helium (symbol He) is a colorless, odorless, nonmetallic gas that is produced abundantly by the nuclear fusion in all stars and is found in smaller amounts on Earth. It was discovered by the British scientist—and founding editor of the journal Nature—Joseph Norman Lockyer in 1868, while he was studying a solar eclipse with a spectroscope, an instrument that breaks light up into a spectrum. If an element is heated up enough to glow, the emitted light produces a unique spectrum when refracted through a prism. Lockyer noticed that the spectrum of the Sun's corona, which is visible only during a solar eclipse, contained lines produced by an unknown element. He named the element helium from helios, the Greek word for “sun.” Helios gives us many other words pertaining to the Sun, such as heliocentric and perihelion.

Discover More

Because it is lighter than air, helium is used to fill balloons.

Helium is the best known of the inert gases.

Etymology

Origin of helium

First recorded in 1875–80; from New Latin, from Greek hḗli(os) “the sun” + New Latin -ium noun suffix; -ium

Example Sentences

The escaping helium originates from the planet's extended upper atmosphere, known as the "exosphere."

From Science Daily

Once, it was included in a bill to shore up the nation’s helium supply.

From Los Angeles Times

Call it the parade’s final magic trick: making hundreds of thousands of cubic feet of helium, dozens of floats, and throngs of fans vanish.

From The Wall Street Journal

The flight quickly went off course because of helium leaks in the vehicle’s propulsion system and the temporary failure of five thrusters that maneuver the craft.

From The Wall Street Journal

Cosmic dust forms when stars explode or when comets break apart, and much of it carries a rare version of helium called helium-3 after passing near the sun.

From Science Daily