General Chemistry Element –composed of atoms Nucleus –protons (+) and neutrons (0) Electrons (-)

General Chemistry Molecule –a group of atoms held together by chemical bonds

General Chemistry Bonds –covalent bonds form when electrons are shared

General Chemistry Bonds –ionic bonds form by attraction between particles with opposite charges

Water H 2 O covalent bonds hold the 2 hydrogen & 1 oxygen together

Figure 5.2

Water Overall water is neutral but… Water molecules have an uneven distribution of charge = polar –H ends are positive –O end is negative

Water Hydrogen Bonds –form between hydrogen of one water molecule and the oxygen of another

Figure 5.3

Figure 5.5

Water is the universal solvent Solution (saltwater) =solute (salt) in a solvent (water)

Seawater 96.5% water & 3.5% solutes

Salinity total concentration of all dissolved inorganic solids Average of the entire ocean = 3.5% or 35 ppt (35 o / oo ) (35 parts per thousand) Salinity can change from place to place

The Ocean is in Chemical Equilibrium Average salinity is not changing over long time periods Overall amount of dissolved salts in the ocean is nearly constant Additions of salts are balance by the removal of salts

Figure 5.19