So it must form two covalent bonds to obtain 2 more electrons than it normally has by itself. The picture to the left will help you visually to see how covalent bonds can help increase the number of electrons that an atom can have. Oxygen can either form two single bonds or one double bond. Water is a good example where Oxygen attaches to 2 ...

Taste Buds Burial dating uses the differential radioactive decay of 2 cosmogenic elements as a proxy for the age at which a sediment was screened by burial from further cosmic rays exposure. Luminescence dating techniques observe 'light' emitted from materials such as quartz, diamond, feldspar, and calcite. Many types of luminescence techniques ...