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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 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 | 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
  • 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 – expert written, user friendly element information
    The chemical element helium is classed as a noble gas and a nonmetal It was discovered in 1895 by William Ramsay Note: At normal atmospheric pressure, helium does not solidify and so has no melting point The melting point quoted above is under a pressure of 25 atmospheres
  • Helium Element- Properties, Uses, Toxicity, Safety - Science Info
    Helium element, with the symbol He and atomic number 2, is the second most abundant chemical element in the universe It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas at the top of the periodic table of noble gases It has the lowest boiling and melting points of any element
  • Helium - New World Encyclopedia
    In the present-day universe, almost all new helium is created as a result of the nuclear fusion of hydrogen in stars On Earth, it is produced by the radioactive decay of much heavier elements After its creation, part of it is trapped with natural gas, at concentrations of up to 7 percent by volume
  • Helium: A Natural Gas Byproduct with Unique Properties and Uses
    Helium is used for a lot more than party balloons In its most important use, liquid helium is used to cool MRI machines in hospitals Its diverse properties allow helium gas and liquid helium to be used in many ways
  • Helium: Element Properties and Uses - samaterials. com
    Helium is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gases group in the periodic table It is the second lightest element in the universe, after hydrogen, and is primarily found in stars, including our sun





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