section_path: Compounds/Oxides and other inorganic compounds
section_name: Oxides and other inorganic compounds
paragraph_text: Oxides and other inorganic compounds
  
  Water (H O) is an oxide of hydrogen and the most familiar oxygen compound. Hydrogen atoms are covalently bonded to oxygen in a water molecule but also have an additional attraction (about 23.3 kJ/mol per hydrogen atom) to an adjacent oxygen atom in a separate molecule. These hydrogen bonds between water molecules hold them approximately 15% closer than what would be expected in a simple liquid with just van der Waals forces.
  
  Due to its electronegativity, oxygen forms chemical bonds with almost all other elements to give corresponding oxides. The surface of most metals, such as aluminium and titanium, are oxidized in the presence of air and become coated with a thin film of oxide that passivates the metal and slows further corrosion. Many oxides of the transition metals are non-stoichiometric compounds, with slightly less metal than the chemical formula would show. For example, the mineral FeO (wüstite) is written as Fe 1 − x O {\displaystyle {\ce {Fe}}_{1-x}{\ce {O}}}, where x is usually around 0.05.
  
  Oxygen is present in the atmosphere in trace quantities in the form of carbon dioxide (CO). The Earth's crustal rock is composed in large part of oxides of silicon (silica SiO, as found in granite and quartz), aluminium (aluminium oxide Al O, in bauxite and corundum), iron (iron(III) oxide Fe O, in hematite and rust), and calcium carbonate (in limestone). The rest of the Earth's crust is also made of oxygen compounds, in particular various complex silicates (in silicate minerals). The Earth's mantle, of much larger mass than the crust, is largely composed of silicates of magnesium and iron.
  
  Water- soluble silicates in the form of Na SiO, Na SiO, and Na Si O are used as detergents and adhesives.
  
  Oxygen also acts as a ligand for transition metals, forming transition metal dioxygen complexes, which feature metal– O. This class of compounds includes the heme proteins hemoglobin and myoglobin. An exotic and unusual reaction occurs with PtF, which oxidizes oxygen to give O PtF, dioxygenyl hexafluoroplatinate.