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.