Mary Lou Bunul, aged 13; Tuscon, Arizona for question:
How is oxygen made?
Oxygen is one of the 90 odd elements of which the world is made, In one form or another it is the most plentiful stuff in the world. There are 23 pounds of it in every 100 pounds of ordinary air. There are 8 pounds of oxygen in every 9 pounds of water. And oxygen makes up almost half the weight of the rocks that form the earths crust‑,
Free in the air, oxygen is an odorless, tasteless, invisible gas. At minus 193 degrees Centigrade it cools to a pale blue liquid. At minus 21.9 degrees Centigrade it chills to a pale blue solid, Since it is an element, oxygen is made of single atoms .‑ all alike. The nucleus of the oxygen atom is eight neutrons and eight protons charged with positive electricity. Eight electrons, charged with negative charge to shell around‑ the—nucleus ‑ Like all atoms it is electrically neutral,
No one can arrange atomic particles in this design to make an atom of oxygen. So no one can create oxygen. However, it is easy to recover from various mixtures. We can separate the oxygen from water, from the air and from certain chemical compounds.
Oxygen is one of the busiest of elements. This is because of the shape of its atom. Two electrons form the inside shell, which is all any atom can hold in the inside shell. Six atoms are in the second shell, An atom can hold eight atoms in this shell. The oxygen atom is hungry to fill this shell with two more electrons. It grabs loose electrons from other atoms.
The hydrogen atom has but one electron. When an oxygen atom grabs an electron from each of two hydrogen atoms it becomes charged with extra negative electricity. To become comfortably neutral again, it must team up with the rest of the two robbed hydrogen atoms. So the three atoms tie up to become one molecule of water.
A current of electricity through water can undo this welding job. It forces the molecules to break apart into the original atoms of oxygen and hydrogen and oxygen gas. Much of the commercial oxygen is shocked from water by this process called electrolysis.
Certain chemicals can be forced to give up their oxygen merely by heat, Potassium chlorate gives up its oxygen when heated with a dash of manganese dioxide,
Another way to gather pure oxygen is by freezing it out of the air. Each of the gases in the air has its own freezing and melting point, Below its own special bailing point, each becomes a liquid, This is one way to separate them. The oxygen runs off as a liquid when the air is chilled to minus 193 degrees, Centigrade.