from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A colorless, odorless inert gaseous element occurring in natural gas and with radioactive ores. It is used as a component of artificial atmospheres and laser media, as a refrigerant, as a lifting gas for balloons, and as a superfluid in cryogenic research. Atomic number 2; atomic weight 4.0026; boiling point −268.9°C; density at 0°C 0.1785 gram per liter. cross-reference: Periodic Table.
from The Century Dictionary.
- noun A hypothetical elementary substance, known only by the lines ascribed to it in the solar spectrum.
from the GNU version of the Collaborative International Dictionary of English.
- noun (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° 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.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun uncountable A
colorlessand inertgas, and the second lightest chemical element(symbol He) with an atomic numberof 2 and atomic weightof 4.002602.
- noun countable A form or sample of the element.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun 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)
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/Share-Alike License
The laggards will be consumer spending, especially on cyclically sensitive items, and housing, where the helium is already starting to come out of the balloon.
In 1868 Sir Norman Lockyer detected a light coming from the prominences of the sun which was not given by any substance known on earth, and attributed this to an unknown gas which he called helium, from the Greek
The sentence “helium is a noble gas” clearly implies a particular definition of ‘noble’: the technical chemical definition, which means something like ‘inert’.
In other words, one could not really argue that helium is more intentional than hydrogen or sulphur.
(Ground-supplied helium is used pre-launch to keep the tank pressurized.)
If helium is that much better than hot air, how much better is hydrogen than helium?
We cannot get too significant quantities of helium from the sun ¬ — which can be viewed as a helium factory 93 million miles away — nor will we ever produce helium in anywhere near the quantities we need from earth-bound factories.
As the uranium and thorium decay, some of the helium is trapped along with natural gas deposits in certain geological formations.
I would guess that the sun is going to get hotter anyway (as it is burning hydrogen and becoming richer in helium) but that stopping human-driven warming will get us another few thousand years to work out a solution to the solar-driven warming.
Thus the maximum velocity reachable by helium is about 3.33 times that for argon.