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Name Oxygen
Atomic Number 8
Atomic Weight 15.9994
Symbol O
Melting Point ( °C ) -218
Boiling Point ( °C ) -183
Density (g/cm3) 1.43
Earth crust (%) 46.71
Discovery (Year) 1774
Group 16
Electron configuration [He] 2s2 2p4
Ionization energy (eV) 13.6181

Oxygen is the 8th element of the periodic table oxygen is located in group 6A, which is a nonmetal group.<ref>Shell, B. (2000). Physics question #127. Retrieved January 30, 2009, from http://www.science.ca/askascientist/viewquestion.php?qID=127</ref> The atomic number of oxygen is 8, so that means it has 8 protons. <ref>http://www.education.jlab.org/itselemental/ele008.html</ref> It is a gas elemnt, and is a part of the nonmetals group on the periodic table. The symbol is O, and the atomic mass is 15,999.

This element is our main (and only) source of breathing and living on this planet, we would be hopeless without it.

Discovery Oxygen accounts for nearly half of the mass on the earths crust. (Crocker,14)<ref>http://www.khemistry4kids.serch=oxygenfindrdef.org</ref> It also counts for two thirds of mass in the human body and nine tenths of the mass in water. Oxygen was discovered by few of the most intellectual beings in history, including the father of modern chemistry himself, Antoine Lavoisier. (Evans,1) An English chemist discovered oxygen in the year 1774 and published his findings. Lavoisier, who was a french chemist, discovered oxygen in 1775. (Julian,10) He was the first to recognize it as an element in the periodic table.

These scientists performed many experiments with this newly found idea they had in their possession, leading up to when he finally discovered the element itself. The experiments involved obtaining oxygen from minerals. Carl Wilhelm Scheele discovered that red-hot manganese oxide produces a gas. Because the experiment produced mild combustion, he decided to name it "fire air" as a result of the substance not charcoal dust. (Mark,4) In 1774, Priestly repeated Scheele's experiments. But this time he only used different equipment . He focused sunlight on a lump of reddish mercuric oxide in an inverted glass container. When the gas finally emitted from the container the results he produced was "5 or 6 times as good as common air". (Ramsden,23) In a succeeding test, a live specimens test subject, it caused a flame to burn intensely and kept a mouse alive about 4 times as long as a similar quantity of air which is an improvement. <ref>http://oxyworld.org/oxygen/oyg07/hm/edu.gov</ref> Joseph Priestly put out a sprig of mint into a transparent, closed space with a candle that burned out. (John,8) After 27 days, he re-lit (PST)the extinguished candle once again, and to his surprise it actually burned perfectly well in the air that previously would not support it. (Sheridan,3)

In another experiment from 1772, Priestly kept a mouse in a jar of air until it collapsed from lack of oxygen. He found that a mouse kept with a plant would survive due to photosynthesis because the plant gives off oxygen. It is the essential element we breathe in order to survive, which gives it an important role on Earth.

History (Gr. oxys, sharp, acid, and genes, forming; acid former) For many centuries, workers realized air was composed of more than one component. The behavior of oxygen and nitrogen as components of air led to the advancement of the phlogiston theory of combustion, which captured the minds of chemists for a century. Oxygen was prepared by workers, including Bayen and Borch, but they didn't know how to collect it, didn't study its properties, nor did they recognize it as an elementary substance.

Priestley is generally credited with its discovery, although Scheele also discovered it independently.

Its atomic weight was used as a standard of comparison for each of the other elements until 1961 when the International Union of Pure and Applied Chemistry adopted carbon 12 as the new basis.



There are three varieties of stable oxygen atoms called isotopes. These have the same properties chemically, but masses that differ by ratios of 16:17:18. The mass of each atom depend on the number of protons and neutrons have all together. Most oxygen atoms contain 8 neutrons and 8 protons, this means that those atoms have the same mass. About 1 in 500 oxygen atoms contain an extra neutron and is 17/16 times more weighted. Approximately, 1 in 2000 contain two extra neutrons and is 18/16 times heavier. The three forms of oxygen atoms are 16O, 17O, and 18O. <ref>http://www.psrd.hawaii.edu/Dec01/Oisotopes.html</ref>


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