Oxygen may be the most important element on Earth. Without Oxygen, there would be no life, no fire, no water and little decay.
On the periodic table, Oxygen is atomic number 8 and has an atomic mass of 16. The nucleus consists 8 protons and 8 neutrons. 8 electrons form a cloud around the nucleus and 6 of them are valance electrons. This means that the outer layer of electrons contains 6 electrons and is looking for two more electrons in order to form a stable shell of 8 electrons. Because oxygen will attract 2 electrons when forming chemical bonds, it is said to have a valence of -2.
Gaseous oxygen is highly reactive. it is the most well know of oxidizing agents. It readily combines with most materials to acquire the two electrons that are lacking in its valence shell. Oxidation reactions are exothermic. They give off more energy than is required to get the reaction started. The most well known oxidation reaction is fire, but the most important oxidation reaction to humans is the reaction in our bodies that enables living creatures to obtain energy from glucose. Without that energy, there is no life. The process of metabolism is a series of biochemical oxidation reactions that slowly breaks down molecules of glucose releasing the energy. While the release is not as obvious as in a fire, the same amount of energy is released by metabolism as would be ifthe glucose were burned in a fire. That energy goes into making muscles contract and producing new tissues in the organism.
Other oxidation reactions include rust, corrrosion and decay. All of these are slow reactions. Rusting occurs when oxygen molecules come in contact with iron and iron aloys. The presence of water is not necessary, but speeds rusting. When oxygen reacts in a similar way with other metals, we call it corrosion. Rust and corrosion damage and destroy metal parts. Decay, on the other hand, can be either damaging or beneficial. We may not like it when food and durable goods decay, but our ecosystem depends on decay. Like rust, decay is a slow oxidation of plant materials, but unlike rust, decay only occurs as a result of the biochemical reactions that take place in living organisms like bacteria and fungi. Because of decay dead plant and animal tissues are broken down into the basic raw materials that plants draw from the soil.
Oxidation reactions proceed rapidly in pure oxygen, sometimes even at explosive speeds. Fortunately the oxygen in our atmosphere is diluted by nitrogen so that everything does not burn up at once. Pure oxygen, however. is used to produce flames with extra heat such as the flame of a welding torch. Pure oxygen is also used to supplement the air being breathed by patients who are not getting enough oxygen into their bodies by normal breathing.
Oxygen is diatomic meaning that each molecule of oxygen gas consists of two atoms bonded together. When acted upon by an electrical spark or certain types of radiation, diatomic oxygen reacts to become ozone. Ozone is triatomic oxygen with three atoms bonded together. Ozone is highly reactive. It seldom lasts very long, but can be used to kill bacteria.
You have heard of the name ozone, because of the current risks to the Earth’s ozone layer. Cosmic rays and ultraviolet light (UV rays) striking the edge of our atmosphere form ozone in the upper atmosphere. This region is called the ozone layer. Because ozone absorbs ultraviolet light, the ozone layer protects humans from overexposure to harmful ultraviolet radiation. Recently we have become aware of thin spots or “holes” in the ozone layer. These are believed to be the action of highly reactive molecules that are light enough to rise into the ozone layer.
Oxygen combines with nonmetals such as sulfur, nitrogen and phosphorus to make clusters of atoms known as sulfates, nitrates and phosphates. These clusters of atoms have their own properties and form their own compounds with unique properties. We are most familiar with the acid forms of these clusters which are the strong acids, sulfuric acid, nitric acid and phosporis acid. We are also familiar with some of their salts such as potassium nitrate, or “salt peter”, used in making gun powder and calcium sulfate or gypsum used in making wall board for our houses.
The backbone of organic molecules is chains of carbon with hydrogen attached. The pure hydrocarbons that make up gasoline, oil and grease have only carbon and hydrogen. The resulting compounds are slippery and insoluble in water. In addition to the carbon and hydrogen, some organic compounds have one or more oxygen molecules, sulfate groups, nitrate groups or phosphate groups in the molecule. The presence of these oxygen containing structures in an organic molecule changes the properties of the chemical. The oxygen in alcohols make them water soluble, but at the same time capable of disolving many otherwise insoluble materials. It is the nitrate groups in amino acids that give amino acids their unique property to chain together to make proteins, the building blocks of living organisms. Organic phosphates serve as energy transfer agents within our bodies to move energy from the place where the glucose is being broken down to the part of the cell where it is needed.
Oxygen is relatively common and highly important to life as we know it, but we tend to ignore it. If you were not reading this article, you might not even be conciously aware of the presence of oygen in the air, but you can not live without it. No cheerful fire in the fireplace without oxygen If you are submerged in water for four minutes, even the best rescue team will probably not be able to resusitate you. If a person flying at 40,000 feet in an unpreasurized aircraft is asked to remove his oxygen mask and sign a letter, his signature will be illegible. If you take the train to the top of Pike’s Peak, you will be surprised that walking around makes you huff and puff for lack of oxygen. Be thankful that 20 percent of our air is oygen.