{medical} Humans need oxygen to survive and take it from the air through the lungs by breathing. Without oxygen the brain can die from anoxia or hypoxia in less than five minutes, with permanent brain damage possible in less than three minutes. An injured person is often given pure oxygen by EMTs and/or paramedics or by a physician in the hospital emergency room. This is to increase the amount of oxygen reaching the brain and other body parts, helping to stave off shock. Medical oxygen is typically found in green canisters with clear plastic tubing attached, and is given to a patient through either a mask or nasal cannulae. The latter is popular in television and movie portrayals of oxygen administration because it allows the actor / patient to speak and act dramatic, but much less effective for the patient.

{fire science} Oxygen is necessary to the basic chemical reaction known as fire. Fire can be put out by depriving it of oxygen, or caused to grow by giving it more oxygen. Oxygen is thus one leg of the fire triangle. Firefighters deprive a fire of oxygen by smothering it with water, sand, foam or some other material. This is one way that water puts out fires; the other is by heat absorption. Oxygen canisters and tents (used medically as above) are a serious fire hazard, which is why smoking is prohibited near them.

A colorless, odorless, tasteless, gaseous chemical element that occurs free in the atmosphere, forming one fifth of its volume, and in combination with water, sandstone, limestone, etc. It is very active, combines with nearly all other elements, is the most common element in the earth's crust, and is essential to life processes and to combustion.

Oxygen was discovered in 1774 by Joseph Priestley in Wiltshire, England by heating mercuric oxide, and independently by Carl Wilhelm Scheele in Upssala, Sweden in 1772, although he did not publish his findings until after Priestley. Priestley originally named the gas "dephlogisticated air" but Antoine Laurent Lavoisier subsequently refuted phlogiston theory and named it oxygen (Greek oxys, acid + Latin gignere, to beget) in 1777, because it was believed that oxygen is present in all acids.

Symbol: O
Atomic number: 8
Atomic weight: 15.9994
Density (at 0°C with 101,325 pascals): 1.429 g/L
Melting point: -218.4°C
Boiling point: -182.96°C
Valence: -2, +2
Ground state electron configuration: [He]2s22p4
Symbol: O
Atomic Number: 8
Boiling Point: 90.188 K
Melting Point: 54.8 K
Density at 300K: 1.429 g/cm3
Covalent radius: 0.73
Atomic radius: 0.65
Atomic volume: 14.0 cm3/mol
First ionization potental: 13.618 V
Specific heat capacity: 0.92 Jg-1K-1
Thermal conductivity: 0.2674 Wm-1K-1
Electrical conductivity: N/A
Heat of fusion: 0.222 kJ/mol
Heat of vaporization: 3.4109 kJ/mol
Electronegativity: 3.44 (Pauling's)

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To the Periodic Table



I warmed myself up tonight, shoveling snow off a patch of concrete. Orion, lying awkwardly on his back, shivered above as he aimed his bow at Taurus snorting high in the southeastern sky. On my way back in, I grabbed a handful of Brussels sprouts, plucked off the plant now surrounded by snow.

Winter is here, as good a reason as any to talk about our inner fire.


I love blasting my propane torch, flashing flame on steel faucets, a blush of condensation dulling the metal, water from fire. (Yep, a lit propane torch emits water--go ahead, check for yourself.)

Electrons trapped in high energy states tumble into the welcoming arms of oxygen, screaming with delight, releasing light and heat as they settle into their pajamas, ready for rest.

Yes, of course, I broke a few rules there. And, yes, of course, it's not quite accurate. It's closer than you might realize.

Our cells need oxygen gas for one reason only--to accept electrons released from food as they travel down their energy gradients, settling into basal states of energy.

The oxygen accept the electrons (and associated protons) to form water. This happens in the innermost regions of our mitochondria, ancient critters subsumed by our forbears.

When you get down to it, we really don't need oxygen at all. Our mitochondrial slaves need it. If a cell doesn't have mitochondria, it has no need for oxygen. Our red blood cells, designed to carry oxygen, use none of it themselves. They have no mitochondria, no need for oxygen. That's why you can keep RBC's packed in plastic bags waiting to be transfused.


Mitochondria are organelles, membrane wrapped particles in your cells that help convert food into a useful form of energy called ATP. Think of ATP as cash energy--no matter where you need a shot of energy in a cell, ATP can provide it. (ATP works by adding instability to compounds--it's like when your crazy Aunt Margarita crashes onto the Thanksgiving table. Things are going to happen.....)

Mitochondria have their own DNA, most closely related to bacteria than to you. They reproduce on their own. They are an ancient life form, far from human, that have been coexisting with larger cells for a long, long time. This is so freaky I don't think it registers with most of my students. Mitochondria allow us to "burn" food down to carbon dioxide and water, releasing the energy caught by chloroplasts in plants.


What is fire? What happens to the fuel, to the oxygen? Most adults here cannot answer this question, and it's pointless if your goal is to make money or get the girl or glom power.

Children love the question, and I doubt most ever get a decent answer. Heck, I know my students don't. We teach chemistry as if it was handed down by Moses himself, the 10 Commandments in one hand, the Periodic Table of Elements in the other. I show them over and over and over again that water comes from a flame, and few can remember this two minutes after the demo is done.

Oxygen gas gets to your mitochondria by bouncing randomly around the inside of a cell. Since most of our cells burn a lot of food, their oxygen concentration is low relative to the fluid bathing them. Just as fart molecules bumble their way across the room to embarrass their producer, oxygen molecules bounce around inside cells until they wander into a mitochondrion.

Red blood cells carry the oxygen molecules through our vessels, and they get dumped off where the oxygen concentration is lowest, needed only by the mitochondria, to produce the ATP needed to keep us alive. This all happens very, very fast.

How fast? Cyanide blocks electrons from reaching oxygen inside the mitochondria. killing within minutes. No oxygen, no fire, no life. I felt my Dad's carcass quickly cool moments after death, no longer warmed by the trillions of mitochondrial furnaces within, his last words spoken an hour earlier, while he still breathed.

Ox"y*gen (?) n. [F. oxygene, from Gr. sharp, acid + root of to be born. So called because originally supposed to be an essential part of every acid.]

1. Chem.

A colorless, tasteless, odorless, gaseous element occurring in the free state in the atmosphere, of which it forms about 23 per cent by weight and about 21 per cent by volume, being slightly heavier than nitrogen. Symbol O. Atomic weight 15.96.

It occurs combined in immense quantities, forming eight ninths by weight of water, and probably one half by weight of the entire solid crust of the globe, being an ingredient of silica, the silicates, sulphates, carbonates, nitrates, etc. Oxygen combines with all elements (except fluorine), forming oxides, bases, oxyacid anhydrides, etc., the process in general being called oxidation, of which combustion is only an intense modification. At ordinary temperatures with most substances it is moderately active, but at higher temperatures it is one of the most violent and powerful chemical agents known. It is indispensable in respiration, and in general is the most universally active and efficient element. It may be prepared in the pure state by heating potassium chlorate.

This element (called dephlogisticated air by Priestley) was named oxygen by Lavoisier because he supposed it to be a constituent of all acids. This is not so in the case of a very few acids (as hydrochloric, hydrobromic, hydric sulphide, etc.), but these do contain elements analogous to oxygen in property and action. Moreover, the fact that most elements approach the nearer to acid qualities in proportion as they are combined with more oxygen, shows the great accuracy and breadth of Lavoisier's conception of its nature.


Chlorine used in bleaching.

[Manufacturing name]


© Webster 1913.

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