Helium (Greek helios,"sun"), symbol He, inert, colorless, odorless gas element. In group 18 of the periodic table, helium is one of the noble gases. The atomic number of helium is 2.
Pierre Janssen discovered helium in the spectrum of the corona of the sun during an eclipse in 1868. Shortly after it was identified as an element and named by the chemist Sir Edward Frankland and the British astronomer Sir Joseph Norman Lockyer. The gas was first isolated from terrestrial sources in 1895 by the British chemist Sir William Ramsay, who discovered it in cleveite. In 1907 Sir Ernest Rutherford showed that alpha particles are the nuclei of helium atoms.
II PROPERTIES AND OCCURRENCE
Helium has monatomic molecules, and is the lightest of all gases except hydrogen. Helium solidifies at -272.2° C; helium boils at -268.9° C. The atomic weight of helium is 4.0026.
Helium, like the other noble gases, is chemically inert. Its single electron shell is filled, making possible reactions with other elements extremely difficult and the resulting compounds quite unstable. Molecules of compounds with neon, another noble gas, and with hydrogen have been detected.
Helium is the most difficult of all gases to liquefy and is impossible to solidify at atmospheric pressure. These properties make liquid helium extremely useful as a refrigerant and for experimental work in producing and measuring temperatures close to absolute zero. L...
Sulfur goes back to the ancient times but it was called brimstone. In 1979, a French chemist named Antoine Lavoisier recognized sulfur was an element and added it to his list of elements. The element sulfur is considered a nonmetal and is the 10th most abundant element in the universe. On the periodic table sulfur is in group sixteen and it is a representative element. Sulfur has an atomic mass of 32.07 with an atomic number of 16. There are three energy levels for sulfur the first energy level is two, the second energy level is eight, and the third energy level is six.
The adiabatic demagnetization refrigeration (ADR) cycle, or “one-shot,” cycle. This cycle was first proposed by Debye (1926) and Giauque (1927) as a means of achieving temperatures below the boiling point of helium [13].
Just like many other scientific discoveries, the discovery and isolation of lithium was a group effort. In 1817, a Swedish scientist by the name of Johan Arfwedson was the first person to discover Lithium. While doing an analysis on the mineral petalite in 1817, Arfwedson found this soft, silver-white element. Jons Jakob Berzelius, another Swedish chemist, named the element the Greek name “lithos.” Later on, the element’s name was then changed to lithium. Although lithium had finally been discovered, none of the aforementioned scientists were able to isolate pure lithium without it being attached to its salts. It was not until 1821 when two English chemists by the names of Sir Humphrey Davy and William Thomas Brande isolated lithium by electrolyzing lithium oxide (LiO2).
Neptune was discovered through a discrepancy in Uranus’s orbit. Uranus’s orbit was not moving how astronomers predicted it would. They could not find an elliptical orbit that fit Uranus’s trajectory. They therefore assumed that there had to be another planet that’s gravitational pull was effecting Uranus. Johann Galle was the first to find Neptune in 1846, even though many before him had mathematically predicted where this new planet would be. The planet was named Neptune and two astronomers who had predicted mathematically where it would be are credited with finding it not Galle.
One of the first inventions but more so of a discovery was the idea of nuclear fusion. It was discovered by a German scientist in february of 1939. This led to the invention of the atomic bomb. The atomic bomb was only used twice both times by the U.S. near the end of the war first on Hiroshima then on Nagasaki(Atomic Bomb).
In 1924, the Indian physicist S. N. Bose developed an alternate law of radiation which modified Planck's laws to include a new variety of particles, namely, the boson. He sent off his theory to Einstein for revision and translation, and Einstein swiftly came up with some additions to the theory. He expanded the laws to incorporate the mass of the boson, and in doing so theorized a strange phenomenon. He predicted that when atoms of a gas came together under cold enough temperatures, and slowed down significantly, that they would all assume the exact same quantum state. He knew that this slow quantum gas would have strange properties, but wasn't able to get much further by theorizing. This phenomenon, which came to be known as a Bose-Einstien condensate, was an incredible leap in quantum theory, but it wasn't demonstrated until 1995 when Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman made the first Bose-Einstein condensate with supercooled alkali gas atoms. Although this development didn't come until late in the 20th century, many of these strange properties were observed in supercooled He4 by Dr. Pyotr Kapitsa. Helium became the standard for observing superfluid phenomenon, and most new superfluid properties are still observed first in Helium 4.
Now the octet rule says that an atom likes to achieve stability by ensuring they have eight valence electrons in their outermost level. Atoms lose or gain valence electrons to achieve the full outer level and they do this by bonding with other atoms. Atoms can bond with each other as in the case of O2 or with different atoms as in the case of H2O. (Timberlake) Only Hydrogen (H) and Helium (He) like to only have two valence electrons.
Lithium Though the drug lithium is used for a number of disorders ranging from acute depression to eating and personality disorders (Paykel, 1992), it's primary use is for bipolar disorder, also known as manic depression. Patients with bipolar disorder "between two poles: depression and its opposite, mania" (Kalat,2004), often with periods of normal behavior in between (Jamison,1993). In addition, the patient is also prone to "mixed episodes" in which symptoms of both mania and depression are present. Intensity of these episodes can range from mild to dangerous, as in the case of a manic depressive mother who severed the arms of her 10 month old daughter (Associated Press, 2005).
Chlorine was discovered in 1774 by Carl Wilhelm Scheele. He obtained it through the reaction of the mineral pyrolusite (manganese dioxide, MnO2) with hydrochloric acid (HCl, then known as muriatic acid). Scheele thought the resulting gas contained oxygen. Sir Humphry Davy proposed and confirmed chlorine to be an element in 1810, and he also named the element.
In 1817, an aging Swedish chemist was pouring over his work on a late afternoon in Stockholm, Sweden. He was analyzing a strange ore named Petalite that had been procured from an island off the coast of Sweden called Utö. The ore Petalite (which is now recognized to be LiAl(Si2O5)2) had been discovered by a Brazilian scientist, José Bonifácio de Andrada e Silva towards the end of the 18th century on a visit to Sweden. This Swedish scientist, Johann August Arfvedson, detected traces of an unknown substance in his sample of Petalite. This was the first discovery of Lithium.
The planet Neptune gets its name from the ancient Roman god of the sea. Along with Jupiter, Saturn, and Uranus, it is one of the immense, gaseous outer planets called Jovian, meaning “Jupiter-like.” Unlike the inner, Earth-like planets, these gas giants have no solid surfaces. Neptune is normally the eighth planet from the sun.
Uranium was discovered by Martin Heinrich Klaproth, a German chemist, in the mineral pitchblende (primarily a mix of uranium oxides) in 1789.Klaproth, as well as the rest of the scientific community, believed that the substance he extracted from pitchblende was pure uranium, it was actually uranium dioxide (UO2). After noticing that 'pure' uranium reacted oddly with uranium tetrachloride (UCl4), Radioactivity was first discovered in 1896 when Antoine Henri Becquerel, a French physicist, detected it from a sample of uranium. Today, uranium is obtained from uranium ores such as pitchblende, uraninite , carnotite and autunite as well as from phosphate rock , lignite (brown coal) and monazite sand . Since there is little demand for uranium metal, uranium is usually sold in the form of sodium diuranate , also known as yellow cake, or triuranium octoxide).
Gases are also very low in density. The average gas is 1000 times less than that of the average liquid. The volume of gas varies with many things including temperature and pressure. These are explained in Charles's and Boyle's laws.
Scientists from earlier times helped influence the discoveries that lead to the development of atomic energy. In the late 1800’s, Dalton created the Atomic Theory which explains atoms, elements and compounds (Henderson 1). This was important to the study of and understanding of atoms to future scientists. The Atomic Theory was a list of scientific laws regarding atoms and their potential abilities. Roentagen, used Dalton’s findings and discovered x-rays which could pass through solid objects (Henderson 1). Although he did not discover radiation from the x-rays, he did help lay the foundations for electromagnetic waves. Shortly after Roentagen’s findings, J.J. Thompson discovered the electron which was responsible for defining the atom’s characteristics (Henderson 2). The electron helped scientists uncover why an atom responds to reactions the way it does and how it received its “personality”. Dalton’s, Roentagen’s and Thompson’s findings helped guide other scientists to discovering the uses of atomic energy and reactions. Such applications were discovered in the early 1900’s by using Einstein’s equation, which stated that if a chain reaction occurred, cheap, reliable energy could b...