Oxygen

Oxygen is a chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, being the most electronegative and otherwise the most common element in the Earth's crust. Oxygen is a highly reactive nonmetal and an oxidizing agent that readily forms compounds with most elements. Its essential role in respiration has led to its name, from the Greek words oxys ('sharp, acid') and -genes ('producer').