Oxygen has eight electrons. Therefore, its atomic number is 8. It has two electrons in its first shell and six electrons in its second shell.
Oxygen is a tasteless, odorless and colorless gas at room temperature and normal pressure, though in its liquid and solid forms, it is pale blue.
Oxygen makes up 21 percent of the air of the Earth's atmosphere and makes up two-thirds the weight of the human body. Most living things need oxygen to live, and most fuels need oxygen to burn.
Oxygen was discovered independently in 1774 by Joseph Priestley in England and Carl Scheele in Sweden.