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Citaat:

Helium
Helium n.
1. 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. [From Greek helios, sun.]
"The American Heritage® Concise Dictionary," (c) 1994 Houghton Mifflin Company. (c) 1994 INSO Corporation. All rights reserved.
Helium is non-toxic and non-flammable and is not affected by cold or warm storage. Helium in the tank is under pressure and must be handled with care: do not drop the tank and make sure the nozzle is tight and does not leak. DO NOT INHALE HELIUM!

Citaat:

The essentials
Name: helium
Symbol: He
Atomic number: 2
Atomic weight: 4.002602 (2) g r
CAS Registry ID: 7440-59-7
Group number: 18
Group name: Noble gas
Period number: 1
Block: p-block

Description
Standard state: gas at 298 K
Colour: colourless
Here is a brief description of helium.

Helium is one of the so-called noble gases. Helium gas is unreactive, colourless, and odourless. Helium is available in pressurised tanks.

Elemental helium is a colourless odourless monoatomic gas. Helium is the second most abundant element in the universe after hydrogen. a particles are doubly ionised helium atoms, He2+.

Citaat:

Helium (He)
Atomic number: 2
Symbol: He
Atomic weight: 4.0026
Boiling Point (C): -268.9
Melting Point (C): -269.7
Density: .126
heatVapor: 0.02
heatFusion: 0.005
Electrical Conductivity: --
Thermal Conductivity: 0.0003
Specific Heat Capacity: 1.25

http://www.howstuffworks.com/helium.htm
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