Discovery and History of Oxygen
In 1608, Cornelius Drebbel had shown that heating saltpetre (potassium nitrate, KNO3) released a gas. This was oxygen (O) although it was not identified as such, it was formally discovered first by Joseph Priestley in Wiltshire, England and independently by Carl Wilhelm Scheele in Uppsala, Sweden. It's name comes from the Greek 'oxy genes', meaning acid forming.
Oxygen first appeared in the Earth’s atmosphere around 2 billion years ago, accumulating from the photosynthesis of blue-green algae. Photosynthesis uses energy from the sun to split water into oxygen and hydrogen. The oxygen passes into the atmosphere and the hydrogen joins with carbon dioxide to produce biomass.
Structure of Oxygen
- The Atomic number for oxygen is 8
- The average atomic mass of Oxygen is 15.999 AMU
- Oxygen has three stable isotopes, O-16, O-17, O-18
- Oxygen has 8 protons, 8 electrons, and 8 neutrons
Occurence in Nature
Oxygen occurs mainly as an element in the atmosphere. It makes up 20.948 percent of the atmosphere. It also occurs in oceans, lakes, rivers, and ice caps in the form of water. Nearly 89 percent of the weight of water is oxygen. Oxygen is also the most abundant element in the Earth's crust. Its abundance is estimated at about 45 percent in the earth. In addition, oxygen is thought to be the third most abundant element in the universe and in the solar system. That makes it almost twice as abundant as the next most common element, silicon.
Oxygen occurs in all kinds of minerals. Some common examples include the oxides, carbonates, nitrates, sulfates, and phosphates. Oxides are chemical compounds that contain oxygen and one other element. Calcium oxide, or lime or quicklime (CaO), is an example. Carbonates are compounds that contain oxygen, carbon, and at least one other element. Sodium carbonate, or soda, soda ash, or sal soda (Na-2 CO-3 ), is an example. It is often found in detergents and cleaning products.
Uses of Oxygen
Oxygen is necessary for the survival of all animal life on Earth. Animals breathe in oxygen and breathe out carbon dioxide.
One important use of oxygen is in medicine. People who have trouble breathing are given extra doses of oxygen. In many cases, this "extra oxygen" keeps people alive after they would otherwise have died.
But oxygen has many commercial uses also. The most important use is in the manufacture of metals. More than half of the oxygen produced in the United States is used for this purpose. Oxygen usually ranks third in the list of chemicals produced in the United States each year. In 1996, about 668 billion cubic feet of oxygen was manufactured in the United States. The gas is prepared almost entirely from liquid air.
- Oxygen has other interesting uses. For example, it is used in rocket fuels. It is combined with hydrogen in the rocket engines. When hydrogen and oxygen combine, they give off very large amounts of energy. The energy is used to lift the rocket into space.
- The first person in Western Europe to describe the "parts" of air was Italian artist and scientist Leonardo da Vinci (1452-1519). Leonardo pointed out that air is not entirely used up when something is burned in it. He said that air must consist, therefore, of two parts: one part that is consumed in burning and one part that is not.