- Oxygen (Wikipedia)
Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth’s most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas currently constitutes 20.95% of the Earth’s atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth’s crust in the form of oxides.
- St. Patrick’s Catholic Church, San Francisco (Wikipedia)
St. Patrick’s Catholic Church is a Roman Catholic church in San Francisco, California, founded in 1851. It is located at 756 Mission Street, between 3rd and 4th streets, across the street from Yerba Buena Gardens in the heart of the South of Market district.
