Oxygen Definition and 25 Discussions

Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. After hydrogen and helium, oxygen is the third-most abundant element in the universe by mass. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Dioxygen provides the energy released in combustion and aerobic cellular respiration, and many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form (allotrope) of oxygen, ozone (O3), strongly absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. However, ozone present at the surface is a byproduct of smog and thus a pollutant.
Oxygen was isolated by Michael Sendivogius before 1604, but it is commonly believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774. Priority is often given for Priestley because his work was published first. Priestley, however, called oxygen "dephlogisticated air", and did not recognize it as a chemical element. The name oxygen was coined in 1777 by Antoine Lavoisier, who first recognized oxygen as a chemical element and correctly characterized the role it plays in combustion.
Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.

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  1. G

    Calculating atmospheric partial pressure of oxygen

    I study genotype-environment associations in alpine species. I frequently see altitude as the sole predictor of partial pressure of oxygen in the literature concerning hypoxia adaptations. However, I understand that partial pressure of oxygen is also influenced by temperature, humidity, and...
  2. martijn_tholen

    Propane/Oxygen - from Cylinder to Oxy/Fuel cutting torch

    For one of our projects we are at present using quite large amounts of gas & oxygen. What I was trying to figure out was how to calculate the total available amount of gas in a cylinder (be that either Propane/Oxygen or Propylene (Propene)) and then to determine whether or not -given a certain...
  3. Epsilon Eridani

    Turning oxygen into fluorine in our atmosphere

    Summary:: Hypothetical discussion of a method to turn oxygen into fluorine through the use of another chemical and also discussing the biological effects of fluorine. Hello, I'd like to start this by saying my knowledge of chemistry is extremely basic. I barely graduated chemistry in high...
  4. M

    What does HC3 mean in 'His HC3'?

    My lecturer said it means: "3rd residue, C-terminal to Helix 'H'" but that makes no sense. If it's the 3rd residue then it can't be on the C-terminal, because the C-terminal is at the end of a massively long sequence of residues. Visa versa if it's on the C-terminal then it can't be the 3rd...
  5. J

    I Bose Einstein Condensate For Oxygen 16 and Oxygen 18

    I am interested in whether or not Bose Einstein condensates have been realized for spin zero stable oxygen isotopes and if so, the maximum density achieved for these condensates. I understand that the quantum spins of oxygen 16 and oxygen 18 are both zero so such condensates would seem to be...
  6. Ygggdrasil

    2019 Nobel Prize in Physiology or Medicine

    Today, the 2019 Nobel Prize in Physiology or Medicine was awarded to three scientists who study how cells sense and respond to changes in oxygen levels: https://www.nobelprize.org/prizes/medicine/ These three scientists were previously awarded the Lasker Prize for Basic Medical Research in...
  7. M

    Can you separate hydrogen and oxygen molecules?

    Is separating hydrogen and oxygen molecules possible? If so, how?
  8. menniandscience

    Seeds and oxygen

    hi anyone and everyone! why do seeds need oxygen before they grow, in the time they are waiting for the right conditions to grow thanks
  9. C

    B The Most Primitive Star-Forming Galaxy Ever Found

    Lying 620 million light-years away, this galaxy has the lowest oxygen abundance ever seen in a star-forming galaxy. Link: New Scientist
  10. Robert House

    Fire suppression in a sealed system

    Here is the scenario. An astronaut is conducting experiments inside of a laboratory module within a space station when all of a sudden, a fire breaks out. The astronaut escapes from the laboratory module he was currently using and then proceeds to seal it off using an airlock. He then...
  11. I

    Expressing concentrations as a percent

    You measure the concentration of O2 in seawater to be 5.0 mg O2/L H2O. Express this concentration as a percent. Question 2: The Earth's atmosphere contains 21% O2/L of air. How much more oxygen does the atmosphere hold than seawater from the previous question? So for question one I got 0.01%...
  12. cookiemonster13

    Oxygen formation in Earth water

    I always wondered why they say water and photons created the first microbes which later evolved and produced oxygen which filled our oceans and atmosphere. So how could have water existed without oxygen? I tried to look up and came up with different explanations, but it doesn't make sense.
  13. Metals

    Nitrous oxide questions

    Now I'm aware of how at around 300 degrees C N2O breaks apart, resulting in more oxygen in the cylinders. I'm also aware that N2O cools down the air fuel mixture when it evaporates, increasing density and resulting in more volumetric efficiency. What I don't get, is why not just take in more...
  14. RoboNerd

    Complete Combustion - which hydrocarbon will consume more O2

    Homework Statement one gram of each of the following gases is introduced into a 10 L container at 25 degrees C a) propane b) ethane c) methane d) pentane which gas will consume the greatest mass of oxygen upon complete combustion? The solutions says that the right answer is D. I do not know...
  15. M

    What is the total mass of an O atom?

    Homework Statement It's a simple problem. What is the total mass of an oxygen atom? Homework Equations Mass of electrons, protons, and neutrons, as well as their respective amount in an O atom The Attempt at a Solution Knowing the number of e, p, and n in an oxygen atom, I can calculate the...
  16. P

    Find the amount of O2 the blood absorbs in the lung

    Homework Statement 100 ml blood of lung vein contains 14 ml O2. The volume of blood in the left ventricle is 70 ml. Find the amount of O2 the blood absorbs in the lung for a minute. Homework Equations 100ml blood -> 14 ml O2 70 ml blood -> x The Attempt at a Solution Here's what I did 100ml...
  17. GiantSheeps

    Reasons for error in percentage of oxygen in KClO3 lab

    Homework Statement I did this lab on percentage of oxygen in potassium chlorate and I got a percent error of about 30%. I now need to find three reasons for error, and human error does not count. I think one could be that the masses used in calculating the theoretical percentage of oxygen were...
  18. A

    Sulfur problem

    A sample of sulfur having a mass of 1.28 g combines with oxygen to form a compound with a mass of 3.2g. What is the empirical formula. So what i did is found the mass of oxygen which is 1.92g . Then converted the 1.28g S to 0.04 mol. Then converted the 1.92g O2 (as it says oxygen, or should it...
  19. D

    Dissolved Oxygen Content

    As part of my project I am taking part in an experiment which involves the catalytic removal of oxygen through the use of hydrogen. Is there an equation to calculate the dissolved oxygen content so that I can compare the experimental results to theory Thanks
  20. devproject

    Oxygen + Hydrogen from water, it safe?

    hi, my name is jake, I am life in Borneo, the island us smoke caused the affected persons who are not responsible for the burning of our forests, and we are currently in desperate need of oxygen, because here there is only smoke. I saw a youtube video tutorials on how to separate oxygen and...
  21. M

    How long will it take for a gas tank to empty?

    Hello all, I have an oxygen tank that is 10 L in volume, pressurized at 500 barr (pressure can be adjusted down to 1 barr out of the tube), and I want to 'bubble' the oxygen into a beaker of water. I will simply use a tube (diameter is around 0.5 cm) connected from the tank and with the other...
  22. P

    Creating oxygen free environment

    Hello, Say I have air circulating in a low pressure loop at 200C, and there are two openings; one for introducing steam and another that allows excess gases to exit. Through experimentation, I know that purging this loop with steam will bring down the oxygen content of this loop to 0% (unless...
  23. S

    How to change the earth's atmosphere to chlorine based?

    Hi, I'm working on a commissioned story, the basic jist of it is aliens colonize earth, begin a lengthy process of terraforming it to fit their toxic homeworld atmosphere. I read somewhere chlorine is the most viable alternative to oxygen in terms of energy production and it's fairly common in...
  24. mike l

    Hydrogen oxygen ignited volume expansion

    Homework Statement there is an expandable container with 1m3 of hydrogen and 1/2 m3of oxygen at stp. the gas is ignited.what is th final volume if there is no heàt lost and the pressure outside the container is 1atm? assume complete combustion Homework Equations other than the ideal gas...
  25. J

    What happens when you remove an excessive amount of electrons.

    Lets take a simple water molecule for example. You can use the photoelectric effect to remove electrons from a molecule. As a thought experiment, let's say you have a contained single water molecule in a vacuum with no impurities. Perfect Vacuum. If you use the Photoelectric effect and beam...