H2O

Water

Water is continuously recycled on Earth. In the water cycle, water evaporates/escapes from the Earth's surface, forms clouds, and fall back to the surface as precipitation

Water is:
    tasteless
    odorless
    transparent
         -sunlight can pass through -> life is able to be sustained in water
   
Water molecules:
    consists of 1 atom of oxygen & 2 of hydrogen (H2O)
    polar
         -Nucleus of oxygen atom attracts electrons much more strongly than the hydrogen nuclei. This              creates a negative electrical charge near the oxygen atom and a positive electrical charge near the            hydrogen atoms.
    can form hydrogen bonds
        -cohesion: ability of water molecules to be able to bond with each other
        -adhesion: ability of water molecules to attach to a surface

Properties that facilitate an environment for life
         -cohesive behavior
         -ability to moderate temperature
         -expansion upon freezing
         -versatility as a solvent

Ice
    lower density than water
         -expands upon freezing
         -floats in water
         -hydrogen bonds line up less efficiently in ice than liquid water
       
Solutions
    effective solvent because it readily forms hydrogen bonds
   
Acids and Bases
     water is the solvent in solution called acids and bases
     solution has higher concentration of hydronium and lower pH than pure water = acid
     solution has lower concentration of hydronium ions and higher pH than pure water = base
     acid turns blue litmus paper red
     base = hydrogen ion acceptor
            accepts hydrogen ions from hydronium ions
     base turns red litmus paper blue
     acid - sour. stings/burns to touch
     base - bitter. slimy to touch. may also burn skin.

Pure water
    neutral
    dissociation of pure water into ions = 2H2O -> H30+    +   OH-
    hydronium ion and hydroxide ion

Liquid water
     hydrogen bonds constantly break & reform

Water
     essential part of most metabolic processes within organism.
     anabolic reaction  -  build up of molecules
     catabolic reaction   -  break down of molecule