Allie+Trickey_MASC

Allie Trickey:) MASC﻿ = HELIUM =  Atomic Number: 2  Symbol: He  Atomic Weight: 4.00260  Shells: 2  Discovery: Janssen, 1868, some sources say Sir William Ramsey, Nils Langet, P.T. Cleve 1895.  Word Origin: Greek: helios, sun. Helium was first detected as a new spectral line during a solar eclipse.

The specific heat of helium gas is unusually high. The density of helium vapor at the normal boiling point is also very high, with the vapor expanding greatly when heated to room temperature. Containers filled with helium gas at 5 to 10 K should be treated as though they contained liquid helium due to the large increase in pressure resulting from warming the gas to room temperature.

Characteristics: Helium is a light, odorless, colorless, invisible, monatomic gas. It can form diatomic molecules, but only weakly and at temperatures close to absolute zero. Helium has the lowest melting point of any element and its boiling point is close to absolute zero. Unlike any other element, helium does not solidify but remains a liquid down to absolute zero (0 K) under ordinary pressures. The voice of someone who has inhaled helium temporarily sounds high-pitched. Uses: Helium is used for filling balloons to make them float in the air. It is also used for and for pressurizing liquid fuel rockets. Mixtures of helium and oxygen are used as an artificial 'air' for divers and others working under pressure. Helium is used instead of the nitrogen in normal air because, after a long dive, helium leaves the body faster than nitrogen, allowing faster decompression.

Helium is used as a gas shield in the vicinity of arc welding and in cryogenics, preventing, for example, any reaction of hot metal welds with oxygen. The gas is used in the semi-condictor industry to provide an inert atmosphere for growing silicon and germanium crystals. It is also used as a high temperature gas in titanium and zirconium production, and as a carrier gas in in gas chromatography.

Helium is foundearly all the helium remaining on Earth is the result of radioactive decay. The major sources of helium are from natural gas deposits in wells in Texas, Oklahoma and Kansas. Helium is extracted by fractional distillation of the natural gas, which contains up to 7% helium.