Notable books in the design pattern genre include: 1  Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). 2  Brinch Hansen, Per (1995). 3  Buschmann, Frank; Meunier, Regine; Rohnert, Hans; Sommerlad, Peter (1996). 4  Schmidt, Douglas C.; Stal, Michael; Rohnert, Hans; Buschmann, Frank (2000). 5  Fowler, Martin (2002).
Answer 1: The oxygen that we currently find in the air has two main sources. The first, and major, source is that oxygen is liberated as a by-product of photosynthetic chemical reactions. The second source occurs in the atmosphere itself when water molecules are split apart after being struck with ultraviolet radiation. This process is called photolysis. The molecule is broken down into one diatomic hydrogen molecule and one free oxygen. The hydrogen molecule is light, and has a quick thermal velocity,so it can escape Earth's atmosphere leaving behind the free oxygen to form a diatomic oxygen molecule. The main source of this atmospheric water was volcanic eruptions and outgassing. Basically before photosynthesis began on large scales, free oxygen molecules in the atmosphere were drawn down in oxidation reactions with free metal ions on the Earth's surface, mainly iron.
Oxygen: the essentials. Oxygen is a Group 16 element. While about one fifth of the atmosphere is oxygen gas, the atmosphere of Mars contains only about 0.15% oxygen.Oxygen is the third most abundant element found in the sun, and it plays a part in the carbon-nitrogen cycle, one process responsible for stellar energy production.n the other hand, ozone is an important component of the atmosphere (the ozone layer) and helps to shield us from harmful ultraviolet rays from the sun. Oxygen gas (dioxygen, O 2) makes up 21% of the atmosphere by volume. It is the most abundant element in the earth's crust (followed by silicon).