helium

[hee-lee-uhm]

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.

helium

/ 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

helium

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

helium

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.

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

Helium is the best known of the inert gases.

Word History and Origins

Origin of helium¹

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

Word History and Origins

Origin of helium¹

C19: New Latin, from _helio- + _-ium ; named from its having first been detected in the solar spectrum

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.

Example Sentences

Researchers measure helium-3 to separate cosmic dust from material originating on Earth.

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"The low metallicity environment, meaning the reduced abundance of elements heavier than hydrogen and helium, is interesting because it's similar to galaxies at earlier cosmological epochs," Sewilo explained.

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In the murky and curious period from early February to June 2007, the subprime mortgage market resembled a giant helium balloon, bound to earth by a dozen or so big Wall Street firms.

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In these extreme conditions, atoms of hydrogen, the lightest element, smash together and combine, forming a new element, helium.

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The stars within these clusters display unusual chemical compositions, with unexpected levels of elements such as helium, nitrogen, oxygen, sodium, magnesium, and aluminum.

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