Oxygen is a chemical element with an atomic number equivalent to 8. At room temperature and in its most common molecular form, which consists of a combination of two atoms, it forms a gas. In the latter case, it represents a significant percentage of the composition of the earth's atmosphere and is essential for respiration and combustion phenomena; it is also odorless, tasteless and colorless.
Oxygen can also be found in a composition of three atoms called "ozone"; This gas, which forms the so-called "ozone layer" in the atmosphere, is responsible for preventing the passage of harmful radiation from the sun while allowing the passage of ultraviolet light, essential for plants to produce their food. It should be noted that when this happens, vegetables expel oxygen in a gaseous state into the environment, which will be used by other living beings so that the nutrients that they incorporate into their body produce energy.
The discovery of oxygen is often attributed to the work of Joseph Priestley (1733-1804) during the year 1772, although Lavoisier had already published appraisals on gas. Prietsley's experiment consisted of heating mercury monoxide, obtaining two vapors. One formed droplets of mercury as it condensed, while the other remained gaseous. Prietsley put it together and began to experiment. He realized that if he brought an ember closer to the gas, it increased its level of combustion, and that if he did it he made mice inhale, they became very active. Finally, Priesley inhaled the gas and felt very light; today it is known that it was oxygen.
Despite its importance to life, oxygen can be lethal to a human being if breathed in pure, since it is generally aspirated in combination with nitrogen. It is also toxic when it forms the chemical compound ozone.
