More information can be found via the WWW links following each element. However, as these links are to other servers on the Internet you will need to use the BACK button on your browser to return to this page. Credits for the photos and principal links can be found at the end of this document. Historically the discovery of oxygen as an element essential for combustion stands at the heart of the phlogiston controversy. Oxygen is a gas at room temperature and is colorless, odorless and tasteless.
Liquid oxygen has a slight blue color.
Virtually every element known forms a compound with oxygen except for some of the noble gases. Two allotropes of oxygen are known. Ozone occurs naturally in the upper atmosphere where it acts as a shield protecting the earth's biosphere from ultraviolet radiation. Closer to the surface ozone can be a nuisance as it is very reactive. Pure sulfur is tasteless and odorless with a light yellow color.