Реферат на тему Helium Essay Research Paper Helium by I
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Helium Essay, Research Paper
Helium
by I ain’t telling you!!!
Pierre Janssen discovered helium in the sun in 1868. Janssen
originally thought it was sodium, but Joseph Norman Lockyer noticed that it
didn’t correspond to the D1 and D2 lines of sodium. He named it the “D3″
line. Lockyer said that the element D3 was unknown on Earth. He and
Edward Franklin concluded on the name Helios after the Greek god of the
sun. Helium is found everywhere in space. All natural gases have at least a
little bit helium in them. Sir William Ramsey first discovered Helium on Earth by in uranium mineral clevite in the year 1895. When he heated the uranium mineral clevite, he noticed a bright yellow light in its spectrum. It looked the same as the D3 line that was found in the sun. It was concluded that this was the element helium. In 1903, Ramsey also discovered that helium is a product of the spontaneous disintegration of radioactive substances. In 1907 Rutheford and Royds demonstrated that all alpha particles are helium nuclei.
The largest compounds of helium are found in the cosmos. About 23 percent of the mass of the universe is helium. This makes it the second most common element behind hydrogen. Helium is mostly concentrated in stars where it combines with hydrogen to create nuclear fusion. Helium is created in stars by nuclear fusion of hydrogen. Helium is found on the Earth as well, but it is not as abundant as it is in space. Only 0.0005 percent of helium occurs in the Earth’s Atmosphere, as opposed to 23 percent in space. On Earth, helium is mostly found as a component in natural gases. This means that they helium is a natural gas. Helium is mostly found in the United States, Especially in Texas, New Mexico, Kansas, Oklahoma, Arizona and Utah. Helium has also been found in smaller quantities in Canada, South Africa, and the Sahara Desert. Helium gas is extracted from natural gases by liquefying the gases at low temperatures and high pressures. With most gases, this produces 98.2 percent pure helium. However, with activated charchol, it produces 99.995 percent pure helium.
Helium, with the symbol He, has an atomic number of 2, and an atomic
mass of 2 AMU’s. It has no color. Helium gas is unreactive, colorless, and
odorless. Helium has an extremely low melting point (-452? F), and boiling
point of close to absolute zero. Helium cannot be solidified by lowering
temperature, but can be by increasing pressure to 25 atmospheres. This
allows for helium to be used as a coolant in many low-pressure devices, such
as rocket engines. It is used to cool liquid hydrogen fuel in these engines.
Due to helium’s ability to function at extremely low temperatures,
helium is the ideal substance to use for cryogenic research. When properly cooled, the temperature of helium can go down to a few Micro-Kelvin’s. Originally for
balloons and blimps (airships), hydrogen was the primary substance used. Hydrogen, with an atomic mass of 1, is the lightest atom, and hence will give you the best performance for airships. However, because hydrogen only has 1 electron in its outermost energy level, it is unstable, and tends to spontaneously combust when mixed with oxygen. One of the most obvious demonstrations of this was the crash of the German airship, the Hindenburg (below left) in 1937 As you can see, the results were not pretty. In more modern times, Helium is used because it is a stable element (below right).
Because of it’s affordable price, and wide array of properties and uses, helium is used all over the world. Everywhere from birthday parties to advanced cryogen research facilities, you are sure to see an application of it. One property that makes helium different than any other element, is its ability to reach extremely cold temperatures. Helium is the ideal substance to use for many different things, and luckily because of its great abundance in outer space, there will never be a shortage of helium.