Mendeleev's Periodic Table > O - Oxygen

O - Oxygen

Oxygen gas was discovered by Swedish pharmacist, Karl Scheele in 1771. Oxygen is prepared in fundamental chemistry using the same process Scheele, Priestley and Lavoisier (who named the element) employed. Comprising 87 percent of the oceans, one fifth of the atmosphere and six out of ten atoms on the crust, oxygen is the most abundant element on the surface of the earth. The gas is colourless, odourless, and tasteless. Liquid and solid oxygen are strongly paramagnetic (contains unpaired electrons). Ozone (O₃) is another allotrope of oxygen. It is formed from electrical discharges or ultraviolet light acting on O₂. It is an important component of the atmosphere (in total amounting to the equivalent of a layer about 3 mm thick at ordinary pressures and temperatures) which is vital in preventing harmful ultraviolet rays of the sun from reaching the earth's surface. Aerosols in the atmosphere have a detrimental effect on the ozone layer. Large holes in the ozone layer are forming over the polar regions and these are increasing in size annually. Paradoxically, ozone is toxic! Undiluted ozone is bluish in colour. Liquid ozone is bluish-black, and solid ozone is violet-black. Oxygen is very reactive and oxides of most elements are known. It is essential for respiration of all plants and animals and for most types of combustion.

Isotopes of O (Oxygen):