Vital Facts About Oxygen - The Element of Sustenance

Fact about the discovery of oxygen
Oxygen is one of the most important elements for the sustenance of life on earth. Here are some interesting facts about oxygen.
All life on earth is based on 4 basic elements: carbon, hydrogen, oxygen and nitrogen, in addition to other important elements such as sulfur and phosphorus. The most abundant amongst these, including its numerous compounds, is oxygen.

This gas is vital to support life as we know it on earth, since it is the gas used in aerobic respiration, the majorly used mode of respiration by advanced organisms on earth.
Chemically speaking, oxygen is a nonmetal. It is gaseous at room temperature. It has the atomic number 8 and mass number 16. It lies in the p-block in the periodic table, in group 16 and period 2.

Oxygen was absent on earth until 2.5 billion years ago. After the emergence of the first autotrophic organisms, atmospheric oxygen started to accumulate. The eventual overload of oxygen culminated in the extinction of anaerobic organisms, which were the prevalent life forms, and paved the way for life as we know it today.
Fascinating Facts about This Invaluable Element
Oxygen was discovered by Swedish pharmacist Carl Wilhelm Scheele around 1771. However, Joseph Priestley is usually given credit for the discovery (in 1774), due to Scheele's discovery remaining unpublished until 1777.
Oxygen is a part of a class of highly electronegative elements known as chalcogens. Chalcogens form the 16th group of the periodic table, and also include sulfur, selenium, tellurium and polonium. As the first chalcogen, oxygen is one of the most electronegative elements in the world, bested only by fluorine.
Oxygen, in its most commonly found dioxygen -- O2 -- form, is an odorless, tasteless, colorless gas at room temperature.
Trioxygen, or ozone -- O3 -- is harmful to humans. Fortunately, it is rarely found on the surface of the earth. It forms the 'ozone layer' in our atmosphere, which blocks most of the UV radiation from the sun.
Oxygen can be liquified at -183° C (the boiling point of oxygen) and solidified at -219° C (the melting point of oxygen). Liquid and solid oxygen bears a pale blue color. Although the liquid and solid forms of oxygen do not occur naturally, the solid form has been discovered to have enormous potential as an efficient rocket fuel, due to its superior oxidizing ability.
About 21% of air is oxygen.
Oxygen dissolves in water. Aquatic organisms (non-mammalian) depend on dissolved oxygen for their survival.
Oxygen doesn't burn, but supports combustion.
The term 'combustion' itself means the exothermic (heat-generating) reaction of a compound with an oxidant. Thus, what we usually call 'burning' is actually nothing but the reaction of the particular substance with atmospheric oxygen. For instance, when wood or gasoline is 'burned', it is simply a process of the hydrocarbons in the wood or gasoline reacting with oxygen to form carbon dioxide and water vapor. Chemically, heat and light are mere byproducts of the reaction, or 'combustion'. Gasoline wouldn't ignite if heated in a vacuum.
Oxygen makes up about 89% (88.8%) of the weight of a water molecule (H2O); although there are two hydrogen atoms, they are very light. Water constitutes 55-60% body weight of an average human. Thus, oxygen constitutes more than half of our body weight!
Oxygen is found in virtually all vital bodily compounds, such as carbohydrates (carbon, hydrogen and oxygen), proteins (carbon, hydrogen, oxygen and nitrogen) and fats.
It is the third most abundant element in the universe after hydrogen and helium. 50% of the crust of the earth by weight is oxygen. It is the most abundant element in the earth's crust. Oxygen's compounds with silica, silicates, are primary components of the earth's mantle.
Oxygen is highly reactive and forms compounds with most elements. It can even form compounds with noble gases under specially created conditions.
Reaction with oxygen is used to differentiate metals and nonmetals. Metals form basic oxides (ex. calcium oxide -- CaO, magnesium oxide -- MgO), while nonmetals form acidic oxides, with the striking exception of the oxide of hydrogen, a nonmetal -- water (ex. carbon dioxide -- CO2, sulfur trioxide -- SO3).
Oxygen is vital in aerobic respiration, i.e., the type of respiration found in humans. Oxygen reacts with glucose to form carbon dioxide, water and energy, the latter of which is used to sustain normal bodily functions.
Atmospheric oxygen is created by autotrophs, i.e., plants. Other living beings depend on the oxygen released by plants to survive. Since plants are living beings themselves, they too need oxygen to survive. However, the net effect of a plant respiring oxygen and releasing oxygen through photosynthesis is that more oxygen is released than gathered.
The level of oxygen in the earth's atmosphere has been seriously depleted due to various factors, such as the industrial revolution, excessive use of carbon-based fuels and the depletion of large tracts of forest areas, creating a net loss in the global volume of dioxygen (O2). According to scientific studies, it has been shown that the concentration level of oxygen in the atmosphere is being depleted by 0.8% in approximately fifteen years.
Oxygen is commercially used in the production of steel, where it removes carbon-based impurities by forming carbon dioxide.
It is necessary for oxidization, or combustion, and also acts as a preserver, sanitizer, deodorizer, and disinfectant. Our cells are energized by oxygen. It regulates all the functions of the body. Our ability to talk, sleep, eat, move, feel, and think are all dependent on the energy that is generated by oxygen. Oxygen is so important to the body that suicide by holding one's own breath, without external assistance, is impossible, since the reflex to inhale is overpowering. However, just in case someone is thinking of it, it would be wise to NOT try that out!