Facts About Helium

What is helium?
Helium is a colourless, odourless, tasteless inert gas lighter than air - at room temperature and makes up about 0.0005% of the air we breathe

Source?
After hydrogen, helium is the second most abundant element in the universe. It has been detected spectroscopically in great abundance, especially in the hotter stars. It is present in the Earth's atmosphere in about 1 part in 200,000. It is present in various radioactive minerals as a decay product, but the major sources are from wells in Texas, Oklahoma and Kansas

Who discovered Helium?
Helium was first discovered by means of the spectroscope in the sun's stmosphere. The discovery, made in 1868 by the strronomer Sir Norman Lockyer, was followed in 1885 by Sir William Ramsay's proof that the element existed on earth. He found it in the uranium ore, clevite. Later it was established that helium is formed by the radioactive decay of many elements which emit a-particles (nuclei of helium atoms) and is contained in all radioactive minerals.

The largest source of helium is natural gas, the richest in helium being the gas from certain wells in Utah, USA. Next to hydrogen, helium is the lightest gas known, has a lifting power equal 92% of hyrogen and the advantage that it is inert and non-inflammable.

Helium = Uses
Helium is used for the inflation of airships, latex balloons and also for cooling. Helium is widely used as an inert gas shield for arc welding; as a protective gas in growing silicon and germanium crystals, and in titanium and zirconium production. It is also used as a cooling medium for nuclear reactors, and as a gas for supersonic wind tunnels. A mixture of 80% helium and 20% oxygen is used as an artificial atmosphere for divers and others working under pressure. Helium is extensively used for filling balloons as it is a much safer gas than hydrogen. One of the recent largest uses for helium has been for pressurising liquid fuel rockets.

Ordinary air contains 1 part in 200,000 of helium. It was the last gaseous element to be liquefied, this being achieved by Omnes in 1908 in Leyden. Liquid helium has many remarkable properties only imperfectly understood. As as being scientifically fascinating it is indispensable in cryogenics (q.v) as a medium for cooling other substances to temperatures near absolute zero.

Hydrogen fusion in the "H bomb" produces helium

HELIUM [helium] , gaseous chemical element; symbol He; at. no. 2; at. wt. 4.0026; m.p. below -272°C at 26 atmospheres pressure; b.p. -268.934°C at 1 atmosphere pressure; density 0.1785 grams per liter at STP ; valence usually 0.

Helium Flotation - Helium balloons
Helium Balloons work by the law of buoyancy. As long as the helium plus the balloon is lighter than the air it displaces, the balloon will float in the air. Helium is a lot lighter than air. The difference is not as great as it is between water and air (a litre of water weighs about 1,000 grams, while a litre of air weighs about 1 gram), but it is significant. Helium weighs 0.1785 grams per litre. Nitrogen weighs 1.2506 grams per litre, and since nitrogen makes up about 80 percent of the air we breathe, 1.25 grams is a good approximation for the weight of a litre of air.

Therefore, if you were to fill a 1-litre soda bottle full of helium the bottle would weigh about 1 gram less than the same bottle filled with air. That doesn't sound like much -- the bottle itself weighs more than a gram, so it won't float. However, in large volumes, the 1-gram-per-litre difference between air and helium can really add up. This explains why blimps and balloons are generally quite large -- they have to displace a lot of air to float.

Natural Occurrence and Preparation
Helium is rare and costly. Wells in Texas (where the Federal Helium Reserve was established in 1925 near Amarillo), Oklahoma, and Kansas are the principal world source. Crude helium is separated by liquefying the other gases present in the natural gas; it is then either further purified or stored for later purification and use

Some helium is extracted directly from the atmosphere; the gas is also found in certain uranium minerals and in some mineral waters, but not in economic quantities. It has been estimated that helium makes up only about 0.000001% of the combined weight of the earth's atmosphere and crust; it is most concentrated in the exosphere, which is the outermost region of the atmosphere, 600-1500 mi (960-2400 km) above the earth's surface. Helium is abundant in outer space; it makes up about 23% of the mass of the visible universe. It is the end product of energy-releasing fusion processes in stars (see interstellar matter ). Uses Helium's noncombustibility and buoyancy (second only to hydrogen) make it the most suitable gas for balloons and other lighter-than-air craft. A mixture of helium and oxygen is often supplied as a breathing mixture for deep-sea divers and caisson workers and is used in decompression chambers; because helium is less soluble in human blood than nitrogen, its use reduces the risk of caisson disease, or the "bends."

Helium is used wherever an unreactive atmosphere is needed,
e.g., in electric arc welding, in growing crystals of silicon and germanium for semiconductors, and in refining titanium and zirconium metals. It is also used to pressurize the fuel tanks of liquid-fueled rockets. Liquid helium is essential for many low temperature applications printed balloons balloons balloon shop

Helium in a Balloon
If you put helium in a balloon and let go of the balloon, the balloon rises until it pops. When it pops, the helium that escapes has no reason to stop -- it just keeps going and leaks out into space. Therefore, in the atmosphere there is very little helium at any given time. The helium that is there comes from alpha particles emitted by radioactive decay. In places that have a lot of uranium ore, natural gas tends to contain high concentrations of helium (up to 7 percent). This makes sense, since the decay of uranium emits lots of alpha particles and a natural gas pocket tends to be a sealed container underground. Helium is cryogenically distilled out of natural gas to produce the helium we put in balloons.

What causes helium balloons to lose their lift after a day or two?
In brief, because the helium leaks out, they shrink, and become heavier than the volume of air they displace. This causes them to lose buoyancy and "sink" in the air. The weight balance that keeps a balloon afloat does not leave a lot of room for leakage, so once a little leaks out the balloon falls.

Sometimes you can catch a balloon right around the time it is neutrally buoyant, and applying heat (your hand, for instance) or cold (rub with ice cube) will change its volume just enough to make it rise or sink in the air.

Lowest Melting Point
Helium has the lowest melting point of any element and has found wide use in cryogenic research, as its boiling point is close to absolute zero. Its use in the study of superconductivity is vital.
Liquid helium (4He) exists in two forms, 4He I and 4He II, above and below 2.174K respectively

The latter is unlike any other known substance. It expands on cooling, its conductivity for heat is enormous and neither its heat conduction nor viscocity obeys normal rules. It remains liquid down to absolute zero at ordinary pressures, but can readily be solidified by increasing the pressure.

Biological Role
Helium has no known biological function, but it is non-toxic.

Helium in the Sun
Helium in the sun is generally believed to be formed by nuclear fusion. This is where nuclei of hydrogen, the lightest element, combine to form helium with huge amounts of energy released. Spectroscopic evidence for the presence of helium in the sun was first obtained during a solar eclipse in 1868. A bright yellow emission line was observed and was later shown to correspond to no known element; the new element was named by J. N. Lockyer and E. Frankland from helios [Gr.,=sun].

Helium was isolated (1895) from a sample of the uranium mineral cleveite by Sir William Ramsay. Properties and Isotopes Helium is less dense than any other known gas except hydrogen and is about one seventh as dense as air.

Helium is Extremely unreactive, it is an inert gas in Group 18 of the periodic table . Natural helium is a mixture of two stable isotopes, helium-3 and helium-4. In helium obtained from natural gas about one atom in 10 million is helium-3. The unstable isotopes helium-5, helium-6, and helium-8 have been synthesized. The alpha particles that are emitted from certain radioactive substances are identical to helium-4 nuclei (two protons and two neutrons). Helium-4 is unusual in that it forms two different kinds of liquids. When it is cooled below 4.22°K (its boiling point at atmospheric pressure) it condenses to liquid helium-I, which behaves as an ordinary liquid. When liquid helium-I is cooled below about 2.18°K (at atmospheric pressure), liquid helium-II is formed. Liquid helium-II has a number of unusual properties. It is sometimes called a superfluid because it has extremely low viscosity. It also has extremely high heat conductivity and expands on cooling. It cannot be contained in an open beaker since a thin film of it creeps up the side, over the lip, and flows down the outside. The study of these phenomena is a part of low-temperature physics. When helium-3 is liquefied and cooled it does not exhibit the properties of liquid helium-II; this difference in properties between helium-3 and helium-4 can be explained in terms of quantum mechanics.