The Chemistry of Life 2.1 Atoms, ions, and molecules
Earths Ocean Waters 25 August 2014 Created by Mr. Allen, FHHS Oceans 71% of the Earths surface is water. Four Oceans (basin): Pacific, Atlantic, Indian, & Arctic. 97% of the water on Earth (3% fresh)
2/3 of fresh water in glaciers & icecaps Created by Mr. Allen, FHHS Spheres of Earth Hydrosphere: total amount of water on a planet regardless of physical state. Cyclic: H2O clouds > Rain/Snow > Lakes, Rivers, Oceans > evaporation into clouds. H2O in living things helps to 1) maintain structure 2) carry materials 3) facilitate chemical reactions.
Created by Mr. Allen, FHHS The Human Connection Food Source, Transportation, Energy The ocean is a renewable energy source: replenishes itself naturally over a short period of time. Nonrenewable resources are exhausted more quickly than they are naturally replaced (natural gas, oil, coal).
Created by Mr. Allen, FHHS Atoms Atoms are the smallest basic unit of matter. Protons p+ have a positive charge Electrons e- have a negative charge Neutrons n0 have a neutral charge All charges are equal. Proton mass Neutron mass
Electron mass << Proton mass Created by Mr. Allen, FHHS Ions An ion is an atom with an uneven # of p+ and e-. Ions are created by removing or adding eValence electrons are on the outer shell. An ionic bond, forms when one e- is transferred from one atoms to another. NaCl illustration on board. Created by Mr. Allen, FHHS
Covalent Bonding Covalent bonds form when atoms share a pair of electrons. A compound s a substance made of different elements. Ex. H2O, CO2, CH4. A molecule is formed when two or more atoms are held together by a covalent bond. Ex. O2, N2 Created by Mr. Allen, FHHS
Properties of H2O H2O is composed of 2 H-atoms and one O-atom. H2O is polar because the O-atoms greater # of p+ have a stronger attraction for e- than the single p+ of the H-atoms. This gives the O-atom a slight negative charge and the H-atom a slight positive charge. Illustration of polar H2O on board Created by Mr. Allen, FHHS
Hydrogen Bond A H-bond occurs when a slightly positive H-atom is attracted to a slightly negative atom. As a result of H-bonding, H2O has 1. A high specific heat. A lot of energy is needed to raise the temperature. 2. Cohesive properties sticks to itself 3. Adhesive properties sticks to other things.
Created by Mr. Allen, FHHS Solutions A solution is a mixture of substances that is the same throughout (homogeneous). Solvent: the component of the greatest quantity. Solute: the component of the smallest quantity. Ex. Blood is 95% H2O (solvent). The other 5% is mostly sugar and proteins (solutes). Remember that polar substances like H2O dissolve
other polar substances and ionic substances very well. Created by Mr. Allen, FHHS Salty Sea 40 billion tons of NaCl carried by rivers into oceans annually. H2O evaporates, NaCl does not (left behind). Volcanic vents spew minerals from ocean floor. Minerals from the atmosphere can be
deposited into the ocean by wind. Created by Mr. Allen, FHHS Acids, Bases, pH An acid releases H+ when it dissolves in H2O A base absorbs H+ when it dissolves in H2O pH (potential of hydrogen), is a scale used to measure hydrogen ion concentration. pH 7 = neutral, pH < 7 is acidic, pH > 7 is basic (aka alkaline)
Created by Mr. Allen, FHHS Salinity and Conductivity Salinity is the measurement of dissolved salts. Other ions in the ocean: (SO4)-2, Mg+2,Ca+2, K+, and HCO-1 Salinity measured in PSU (practical salinity units). Average salinity of ocean water is 35 parts per 1000 The ability of water to carry an electric charge is called conductivity.
Created by Mr. Allen, FHHS Phase Changes Latent heat: the energy loss during a phase change. Freezing, Melting, Condensation: Water occurs naturally in all three states. Water expands are it freezes: froze bite, icefishing, bottle bursting Created by Mr. Allen, FHHS
Estuaries Brackish Water: between fresh and salty Typically in Mangrove Forests and Salt marshes near estuaries. An estuary is an area where the river meets the sea. Sometimes called the nurseries of the sea. Why? Created by Mr. Allen, FHHS
Sea Ice Marine life is very dependent on sea and lake ice Sea Ice 1) insulates the water below 2) reflects sunlight 3) facilitates hunting and den building for polar bears. Created by Mr. Allen, FHHS
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