CharacteristicsSolid and also liquid phases

Helium is at the height of the noble gas group (which also contains neon, argon, krypton, xenon, and radon) and also is the the very least reactive element. Helium has countless interesting characteristics, such as making balloons float and also raising the pitch of one"s voice; these applications are discussed below.

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Introduction

Helium is the 2nd most abundant aspect in the universe, beside hydrogen. Helium is colorless, odorless, and also tasteless. It has actually a very low boiling point, and is monatomic. Helium is small and very light, and is the least reactive of all elements; that does no react with any kind of other facets or ions, so there are no helium-bearing minerals in nature. Helium was an initial observed by researching the sun, and also was named after the Greek word for the sun, Helios.

Physical Properties
Color Colorless
Phase at Room Temperature Gas
Density 0.0002 g/cm3
Boiling Point 4.2 K
Heat that Vaporization 0.1 kJ/mol
Thermal Conductivity 0.15 J/m sec K
Source Natural gas
Atomic Properties
Electron configuration 1s2
Number that Isotopes 7 (2 liquid)
Electron Affinity 0 kJ/mol
First Ionization Energy 2372.3 kJ/mol
Second Ionization Energy 5250.3 kJ/mol
Polarizability 0.198 Å3
Atomic Weight 4.003
Atomic Volume 27.2 cm3/mol
Atomic Radius 31 pm
Abundance
In Earth"s Crust 8x10-3
In Earth"s Ocean 7×10-6
In human Body 0%

Occurrence and also production

Helium is just one of the most abundant aspects in the universe. Large quantities are created in the energy-producing blend reactions in stars. Previously, helium was hardly ever used, because only .0004% of Earth"s setting is helium—that amounts to one helium molecule for every 200,000 waiting molecules, including oxygen, hydrogen, and also nitrogen. However, the exploration of helium-rich wells in Texas, Russia, Poland, Algeria, China, and also Canada has made helium more accessible.

Helium is created in minerals with radioactive decay. Helium is extracted from herbal gas deposits, which frequently contain as much as 10% helium. These organic gas reserves room the just industrially-available resource of helium. The total people helium sources theoretically include up to 25.2 billion cubic meters; the united States contains 11.1 exchange rate cubic meters. The extracted gas is subjected to rememberingsomer.comical pre-purification, making use of an alkaline wash to eliminate carbon dioxide and also hydrogen sulfide. The staying gas is cooled come -200°C, where all materials, other than helium gas, room liquefied.


History

Helium was an initial discovered in 1868 by the French astronomer P. J. C. Jenssen, that was examining the chromosphere of the Sun throughout a solar eclipse. He offered a spectrometer to solve the light into its spectrum, in i beg your pardon each color represents a various gaseous element. He it was observed a brand-new yellow light, concluding that it suggested the visibility of an aspect not formerly known. In 1895, the existence of helium on earth was confirmed by teacher William Ramsay. Heater cleveite (a radiation mineral) released an inert gas, i beg your pardon was found to be helium; this helium is a by-product that the natural degeneration of radioactive elements. The rememberingsomer.comists Norman Lockyer and also Edward Frankland evidenced helium together an element and named the after helios, the Greek word for the Sun.


Applications and hazards

Helium has a number of applications because of its inert nature. Liquefied helium has cryogenic properties, and is used to freeze organic materials for lengthy term storage and later use. Twenty percent of industrial helium use is in wielding and also industrial applications. Helium protects the heated components of steels such together aluminum and also titanium from air. Mixture of helium and also oxygen are offered in tanks because that underwater breath devices: because of its low density, helium gas allows oxygen to stream conveniently through the lungs. Due to the fact that helium stays a gas, also at temperatures low enough to liquefy hydrogen, that is offered as push gas to move liquid hydrogen into rocket engines. The inert nature likewise makes helium beneficial for cooling nuclear power plants.

The most generally known properties of helium is that it is lighter than air. It have the right to levitate balloons during parties and fly blimps over sporting activities stadiums. Helium has actually 92% that the lifting strength of hydrogen; however, it is more secure to use due to the fact that it is noncombustible and also has reduced rate the diffusion than that that hydrogen gas. The famous Hindenburg catastrophe is an instance of the perils of making use of combustible gas prefer hydrogen. Because helium to be previously really expensive only accessible from organic gas make reservation in U.S., Nazi Germany had actually only hydrogen gas in ~ its disposal. The after-effects were devastating, as shown below:

Currently, helium is found in other herbal gas reserves approximately the world. The price of helium has diminished from $2500/ft3 in 1915 to $0.15/ft3 in 1989. Helium is what keeps the Goodyear blimps afloat end stadiums.

Helium is often inhaled native balloons to produce a high, squeaky voice. This practice can be very harmful. Inhaling helium can lead to loss of consciousness and cerebral arterial gas embolism, which have the right to temporarily command to finish blindness. This occurs when blood vessels in the lung rupture, allowing the gas come gain accessibility to the pulmonary vasculature and also subsequently the brain.


Characteristics


Gas and plasma phases

Helium is naturally found in the gas state. Helium is the second least reactive element and also noble gas (after neon). Its short atomic mass, heat conductivity, specific heat, and also sound rate are greatest after hydrogen. Because of the little size that helium atoms, the diffusion price through solids is 3 times higher than that of air and also 65% greater than that of hydrogen. The facet is inert, monatomic in conventional conditions, and also the least water dissolve gas.

At normal ambient temperatures, helium has actually a negative Joule Thomson coefficient. Thus, upon totally free expansion, helium normally heats up. However, listed below its Joule Thomson reverse temperature (32-50 K at 1 atm), the cools when permitted to freely expand. Once cooled, helium have the right to be liquefied through development cooling. Helium is commonly found throughout the cosmos as plasma, a state in i m sorry electrons space not bound to nuclei. Plasmas have actually high electric conductivities and are highly influenced by magnetic and electric fields.


Solid and also liquid phases

Helium is the only aspect that cannot be solidified by lowering the temperature at simple pressures; this have to be add by a pressure increase. The volume of hard helium, 3He and also 4He, have the right to be diminished by much more than 30% by using pressure. Heavy helium has actually a projected thickness of 0.187 ± 0.009 g/mL at 0 K and also 25 bar. Heavy helium additionally has a spicy melting allude and a crystalline structure. There space two creates of fluid helium: He4I and He4II.


Helium I

Helium i is created when temperature falls below 4.22 K and over the lambda point of 2.1768 K. That is a clear liquid that boils when warm is applied and contracts once temperature is lowered. Below the lambda point, helium does not boil, but expands. Helium I has actually a gas-like index of refraction that 1.026 which makes its surface complicated to see. It has a very low viscosity and also a thickness 1/8th the of water. This property deserve to be defined with quantum mechanics. Both helium I and II space quantum fluids, displaying atomic properties on a macroscopic scale as result of the fact that the boiling suggest of helium is for this reason close to absolute zero.


Helium II

At 2.174 K, helium I develops into helium II. Its properties are really unusual, and also the problem is defined as superfluid. Superfluid is a quantum-mechanical state the matter; the two-fluid design for helium II describes why one portion of helium atoms exists in a floor state, flowing through zero viscosity, and also another section is in an excited state, behaving prefer an ordinary fluid. The viscosity that He4II is therefore low the there is no interior friction.

He4II deserve to conduct warmth 300 times much more effectively than silver, making it the finest heat conductor known. Its heat conductivity is a million times that of helium I and several hundred times the of copper. The conductivity and also viscosity of helium II perform not obey timeless rules, yet are constant with the rules of quantum mechanics. As soon as temperature is lowered, helium II expands in volume. It cannot be boiled, however evaporates directly to gas once heated.

In this superfluid state, fluid helium can circulation through slim capillaries or crack much faster than helium gas. It additionally exhibits a climb effect, moving along the surface ar seemingly versus gravity. Helium II creeps follow me the sides of a open up vessel until it reaches a warmer an ar where that evaporates. As a result of the creeping behavior and also the capability to leak swiftly through tiny openings, helium II is very complicated to confine. Helium II additionally exhibits a spring effect. Suppose a chamber allows a reservoir that helium II to filter superfluid and also non-superfluid helium. As soon as the internal of the container is heated, superfluid helium converts to non-superfluid helium to keep equilibrium. This creates intense pressure on the superfluid helium, resulting in the liquid to fountain out of the container.


Isotopes

Helium has eight well-known isotopes but only two are stable: 3He and 4He. 3He is uncovered in only very little quantities contrasted to 4He. The is produced in trace amounts by the beta degeneration of tritium. This kind is found in diversity in stars, as a product of nuclear fusion. Extraplanetary materials have trace amounts of 3He from solar winds. 4He is developed by the alpha decay of heavier radioactive facets on Earth. The is an uncommonly stable isotope since its nucleons space arranged in complete shells.


References

Banks, A. (1989). "Helium." journal of rememberingsomer.comical education 66(11): 945. Draggan, S. (2008). "Helium." Eagleson, M. (1994). Concise encyclopedia rememberingsomer.comistry, Walter De Gruyter Inc. Enghag, P. (2004). Encyclopedia the the elements. Moore, P. And D. Josefson (2000). "Type 2 diabetes is a significant drain on resources." Annals the Emergency medication 35: 300-303. Rosendahl, C. (1938). "New Zeppelin Is described by American Airship Expert." The scientific research News-Letter 33(18): 281-283. Weast, R. And also C. R. Company. (1988). CRC handbook that rememberingsomer.comistry and physics, CRC push Boca Raton, FL.

Outside Links

en.Wikipedia.org/wiki/Helium en.Wikipedia.org/wiki/Goodyear_Blimp

Problems

What happens as soon as a lit tobacco is thrown at a leaking, high-pressured helium cylinder?

a). Nothing

b). The tobacco is incinerated prior to touching the cylinder

c). The cylinder explodes

d). The cylinder becomes a fire thrower

How countless isotopes that helium space known? ______ (Helium gas, or helium II liquid) leaks much faster than the other as soon as stored in a opened cylinder (at STP). What happens once a ar of divided petri food is filled through helium II in ~ 2.173K?

a). That starts boiling.

b). It starts "creeping" end the divider, soon filling up the other sections the the dish.

c). That evaporates and also soon leaves the dish.

d.) the solidifies and also expands, break the dividers of the petri dish, and filling increase the whole dish.

Helium was first discovered v ________.

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Jun-Hyun Hwa ng - college of California, Davis

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