Oxygen is the 8th element, a nonmetal chalcogen. It was discovered by Joseph Priestly in 1774 The name came from the Greek word oxus which means acid and the word gennan which means generate. We usually obtain oxygen by liquifying air and separating the oxygen from the nitrogen [1]. Oxygen is the third most abundant element found in the sun and also plays a part in earth's carbon-nitrogen cycle. Oxygen is very reactive, is a component of hundreds of thousands of organic compounds, and combines with most elements.

1 Properties
2 Occurrences
3 Uses
4 Molecular forms
5 Isotopes
6 History
7 Oxygen in Origins
8 References
9 See Also

Properties

Oxygen molecule

Oxygen is mainly found in air. In liquid or solid form it is clear or a light blue color. The atomic mass average of oxygen is 15.9994, the boiling point is -182.95degC, and the melting point is -218.4degC. Oxygen is odorless and tasteless. Its physical state at room temperature is a gas. Oxygen is reactive and forms oxides with all elements except neon, helium, argon and krypton. It is slightly heavier than air, has no smell or taste, is only a colourless gas, and is sparingly soluble in water.

Occurrences

Oxygen crystals.

Oxygen is the most common component of the Earth's crust and the second most common component of the Earth as a whole as well as being the second most common element of the Earth's atmosphere. Oxygen reacts with some complex transition metals and they act as transporters for some substances. Most Oxygen is found either in the form of silicates, which is an oxide of silicon, or in water, where it makes up 90% of water's weight. It also makes up almost 2/3 of the human body. They have even discovered oxygen in the sun. Transporting oxygen, for whatever reason, is usually done at very high pressure in cylinders made of steel.

Uses

Oxygen has many uses: it is very important in the iron and steel industries. It is also used in its liquid form of as an oxidizer in the fuel systems of large rockets. Oxygen was the original standard for the atomic weights of elements. An obvious use of oxygen is our need to breathe it to stay alive. Oxygen is needed for oxidation reactions including flames. To create fire you need oxygen. Animals and even Plants need oxygen for respiration. Hospitals use oxygen to treat patients with respiratory ailments, as well as to treat pneumonia and gas poisoning. Oxygen is soluble in water but only slightly. The tiny amount found in water doesn't go to waste, since fish need oxygen to breathe (through their gills) to survive. Oxygen gas is also used in many industrial processes. Powdered charcoal mixed with liquid oxygen can be used as an explosive.

Molecular forms

Oxygen appears in two common molecular forms. The classic molecular form of oxygen (O₂, O=O) has two atoms, with a double covalent bond joining them. The other common form, called ozone (O₃, O=OO), has three atoms of oxygen in a resonance configuration. Ozone is a noxious gas and, when found near the ground, is considered a pollutant. But stratospheric ozone protects the earth from excessive ultraviolet light from the sun.

Isotopes

Main Article: Isotopes

Oxygen isotopes are used to extract paleoclimatic information from ice cores and sedimentary limestone. The ratio of oxygen-18 to oxygen-16, is used as an indicator of paleotemperatures since it is related to ocean temperature. The ratio of isotopes can be recorded in the rocks that are forming at that time. There are three main stable varieties of oxygen atoms called isotopes that have the same chemical properties but their masses differ by ratios of 16:17:18.The mass of each atom depends on the total number of neutrons and protons it has. Most oxygen atoms contain 8 neutrons and 8 protons, though some have nine or ten neutrons and weigh proportionately more. All three isotopes have medical purposes.

The connection between isotopes and the temperature is that 0-18 with its 2 extra neutrons is heavier then 0-16 and makes heavier water molecules. The heavier O-18 water molecule needs more energy than an O-16 water molecule to evaporate, and less energy to condense. Thus, cooler water winds up with slightly more O-18 than warmer water. Measuring the oxygen isotope ratios in tiny sea animals gives indications of the water temperature in which the animals lived. In Ice cores, scientists look for "heavy water" made with deuterium (heavy hydrogen) that has O-18 molecules instead of O-16 molecules. The ratio of this water to normal water should indicate the general climate temperature, or at least, the sea temperature from which the water evaporated which formed the snow and ice. Presumably snow and ice with more "heavy water" would have formed from water vapor which evaporated from cold water rather than warm. [2]

History

Oxygen wasn't really invented but rather discovered and described. Two separate people found and described it. Michał Sędziwój, a polish philosopher in the 16th century said that oxygen was "the gas given off by warm nitre as 'the elixir of life'[3]" The man who gave a more complete description was Swedish, named Carl Wilhelm Scheele. It was thought that he found oxygen in 1773 or before, but did not publish until much later. Because it was not published immediately a man named Joseph Priestley published his description in 1775. When the men first found this element they did not call it Oxygen but "dephlogisticated air" since it seemed especially capable of combining with more phlogiston and could keep a fire burning longer than ordinary air. Later the gas was renamed by Antoine Laurent Lavoisier. Its name was taken from Greek roots meaning acid-former because it was thought (incorrectly) that all acid has oxygen in it.

Oxygen in Origins

Oxygen is a problem for secular origins science. If Oxygen were present in the atmosphere at the beginning it would tend to destroy any amino acids formed by lightning. These amino acids would be absolutely necessary for the postulated chance assembly of the first cell. Many have argued that there was no oxygen in the atmosphere when life was formed. However, without oxygen, ozone would not form, and the earth would have no protection from the ultraviolet rays given off by the sun. Today, the quantity of ozone in the high levels of our atmosphere protects from ultraviolet rays, but the early earth without oxygen would have no such protection. Ultraviolet radiation would tend to destroy any complex life molecules that came into sunlight. Either way, oxygen is a difficulty for evolution.