IntroductionWater, H2O, is one of the most important chemical compounds on earth and is commonly considered the basis of life on earth, because it is used in all types of chemical and biological processes, e.g. solvents, protein folding, nucleic acid stability, etc. Water is found in 3 states (solid, liquid and gaseous) and is the most abundant natural substance on earth, covering 75% of the planet. the earth's surface.StructureWater consists of 2 hydrogen atoms and 1 oxygen atom (held together by covalent bonds between the OH atoms) and 2 lone pairs of electrons on the oxygen atom, resulting in the formation of a bent shape with a bond angle of 104.5⁰. These 2 lone pairs of electrons indicate that water has a tetrahedral structure in which oxygen is bonded to 4 hydrogen atoms; 2 covalent bonds and 2 hydrogen bonds (General Chemistry, 2011). Hydrogen bonding "is a specific type of dipole-dipole interaction between the hydrogen atom in a polar bond and an electronegative O, N, or F atom" (Quotes from General Chemistry, 2011 page 405), and is the most strong intermolecular force. The hydrogen bonds in water (Figure 1) mean that water has a high specific heat capacity, this is because, because the hydrogen bonds are strong, a large amount of heat is required (increases the kinetic energy of the hydrogen molecules water), to break them, however water can absorb a large amount of heat and its temperature increases only slightly, while the opposite happens when the heat is released, i.e. its temperature decreases only slightly (General Chemistry, 2011). The presence of hydrogen bonds between water molecules, which allow them to stick together, demonstrates that water is highly cohesive (Biochemistry, 2011). A special type of cohesion is surface tension, in which the...... center of the paper......cal Company http://www.ncbi.nlm.nih.gov/pmc/articles/PMC372788/ pdf/microrev00039-0112.pdf http://www.ncbi.nlm.nih.gov/pubmed/330 7919 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1262463/pdf/biophysj00088-0020 .pdf http://www.lsbu.ac.uk/water/protein2.html - protein folding and denaturation http://www.lsbu.ac.uk/water/protein.html - Protein hydration http://www.lsbu.ac.uk/water/nucleic.html - Nucleic acid http://www.biomedcentral. com/1471-2199/12/21 - Protein diversity http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4335444 – Water behaviorhttp://www.exobiologie.fr/index.php/vulgarisation /chimie-vulgarisation/the-role-of-water-in-the-structure-and-function-of-biological-macromolecules/ - The role of water in the structure and function of biological macromoleculesWikipedia – Protein folding, Water, Hydrophobic interactions, Solvent