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helium    音标拼音: [h'iliəm]
n. 氦



helium
n 1: a very light colorless element that is one of the six inert
gasses; the most difficult gas to liquefy; occurs in
economically extractable amounts in certain natural gases
(as those found in Texas and Kansas) [synonym: {helium}, {He},
{atomic number 2}]

Noble \No"ble\, a. [Compar. {Nobler}; superl. {Noblest}.] [F.
noble, fr. L. nobilis that can be or is known, well known,
famous, highborn, noble, fr. noscere to know. See {know}.]
1. Possessing eminence, elevation, dignity, etc.; above
whatever is low, mean, degrading, or dishonorable;
magnanimous; as, a noble nature or action; a noble heart.
[1913 Webster]

Statues, with winding ivy crowned, belong
To nobler poets for a nobler song. --Dryden.
[1913 Webster]

2. Grand; stately; magnificent; splendid; as, a noble
edifice.
[1913 Webster]

3. Of exalted rank; of or pertaining to the nobility;
distinguished from the masses by birth, station, or title;
highborn; as, noble blood; a noble personage.
[1913 Webster]

Note: Noble is used in the formation of self-explaining
compounds; as, noble-born, noble-hearted, noble-minded.
[1913 Webster]

{Noble gas} (Chem.), a gaseous element belonging to group
VIII of the periodic table of elements, not combining with
other elements under normal reaction conditions;
specifically, {helium}, {neon}, {argon}, {krypton},
{xenon}, or {radon}; also called {inert gas}.

{Noble metals} (Chem.), silver, gold, and platinum; -- so
called from their resistance to oxidation by air and to
dissolution by acids. Copper, mercury, aluminium,
palladium, rhodium, iridium, and osmium are sometimes
included.
[1913 Webster]

Syn: Honorable; worthy; dignified; elevated; exalted;
superior; sublime; great; eminent; illustrious;
renowned; stately; splendid; magnificent; grand;
magnanimous; generous; liberal; free.
[1913 Webster]


Helium \He"li*um\ (h[=e]"l[i^]*[u^]m), n. [NL., fr. Gr. "h`lios
the sun.] (Chem.)
An inert, monoatomic, gaseous element occurring in the
atmosphere of the sun and stars, and in small quantities in
the earth's atmosphere, in several minerals and in certain
mineral waters. It is obtained from natural gas in industrial
quantities. Symbol, He; atomic number 2; at. wt., 4.0026
(C=12.011). Helium was first detected spectroscopically in
the sun by Lockyer in 1868; it was first prepared by Ramsay
in 1895. Helium has a density of 1.98 compared with hydrogen,
and is more difficult to liquefy than the latter. Chemically,
it is an inert noble gas, belonging to the argon group, and
cannot be made to form compounds. The helium nucleus is the
charged particle which constitutes alpha rays, and helium is
therefore formed as a decomposition product of certain
radioactive substances such as radium. The normal helium
nucleus has two protons and two neutrons, but an isotope with
only one neutron is also observed in atmospheric helium at an
abundance of 0.013 %. Liquid helium has a boiling point of
-268.9[deg] C at atmospheric pressure, and is used for
maintaining very low temperatures, both in laboratory
experimentation and in commercial applications to maintain
superconductivity in low-temperature superconducting devices.
Gaseous helium at normal temperatures is used for buoyancy in
blimps, dirigibles, and high-altitude balloons, and also for
amusement in party balloons.
[Webster 1913 Suppl. PJC]



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  • Helium - Wikipedia
    Helium (from Ancient Greek: ἥλιος, romanized: helios, lit 'sun') is a chemical element; it has symbol He and atomic number 2 It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table
  • Helium | Definition, Properties, Uses, Facts | Britannica
    Helium is a chemical element, an inert gas of Group 18 (noble gases) of the periodic table The second lightest element, helium is a colorless, odorless, and tasteless gas that becomes liquid at -268 9 degrees Celsius
  • America Has a Helium Problem - Newsweek
    “Over the past decade, helium has become more scarce and more expensive,” one scientist who relies on the element told Newsweek
  • The world keeps running out of helium. There is now a race to . . . - BBC
    Helium is odourless, extremely light and, unlike another very light element once used in airships, hydrogen, it will never burst into flames
  • About Helium - Bureau of Land Management
    Helium was first identified in 1868 by astronomers studying the sun It is the second most common element in the universe, with only hydrogen being more abundant Here on Earth, Helium is a non-renewable natural resource that is mostly recovered from natural gas deposits
  • Helium - Element information, properties and uses | Periodic Table
    Element Helium (He), Group 18, Atomic Number 2, s-block, Mass 4 003 Sources, facts, uses, scarcity (SRI), podcasts, alchemical symbols, videos and images
  • Helium: An Endangered Element - American Chemical Society
    The second most abundant element in the universe, helium is a product of nuclear fusion and radioactive decay It is the lightest noble gas, colorless, odorless, and inert with a low boiling point
  • Helium Browser
    Helium blocks ads, trackers, phishing websites, and other nonsense by default, thanks to community filters and uBlock Origin Helium blocks all third-party cookies and does its best to prevent fingerprinting No extra steps are needed, and there are no biased exceptions — unlike other browsers
  • Helium | He (Element) - PubChem
    Helium is an inert gas and does not easily combine with other elements There are no known compounds that contain helium, although attempts are being made to produce helium diflouride (HeF 2)
  • Iran war cut off helium from Qatar, and shortages will start . . . - Fortune
    Qatar supplies a third of the world's helium, according to the U S Geological Survey, but the nation had to halt production shortly after the war erupted three weeks ago





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