The Chemistry of Life

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The Chemistry of Life

• Biology Class --- Mrs. Volin
• Chapter 2 Sections 1 2

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C6H12O6 6O2 CO2 H2O

• Write down everything you know about this
  equation!

• Can you name the compounds?
• How many atoms of each element?
• Can you balance the equation?

2-2
3
C6H12O6 6O2 CO2 H2O
6
6
2-3
4
C6H12O6 6O2 CO2 H2O
6
6
Balanced!
2-4
5
C6H12O6 6O2 CO2 H2O
6
6
glucose oxygen carbon
dioxide water
The process is called cellular respiration.
2-5
6
coefficients
C6H12O6 6O2 6 CO2 6H2O
subscripts
2-6
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Atoms

• The smallest fragment of a substance that still
  has the properties of that substance the basic
  unit of matter
  
  

1 cm
100 million atoms
Democritus

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Subatomic particles

• Protons
• Neutrons
• Electrons -
• Nucleus

He atom

• Helium
• Atomic number 2
• Mass number 4 (protons and neutrons)

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element a pure substance that consists entirely
of one type of atom
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Isotopes

• Atoms of the same element that differ in of
  neutrons

• Isotopes of carbon

14C
13C
6
12C
6
6
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Compounds

• Chemical combination of two or more elements in
  definite proportions
• Examples
• Water H2O
• Table salt NaCl

chemical formula
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Chemical bonds

• Covalent bond electrons are shared between atoms

13
H2O

• Single covalent bonds

14

• O2

• Double covalent bond

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• Molecule structure formed when atoms are joined
  together by covalent bonds. The smallest unit of
  most compounds.

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Chemical Bonds

• Ionic bond electrons are transferred from one
  atom to another

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sodium
chlorine

• sodium chloride (NaCl)
• an example of ionic bonds

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Chemical Bonds

• Van der Waals Forces
• Slight attraction that develops between
  oppositely charged regions of nearby
  molecules

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Properties of water
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• 10 protons, 10 electrons water is neutral

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Water molecule is neutral overall Oxygen end of
molecule has slight charge Hydrogen end of
molecule has slight charge
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Water is a polar molecule

• Oxygen end of molecule has slight charge
• Hydrogen end of molecule has slight charge
• d represents partial charge
• Water is polar because there is an uneven
  distribution of electrons between the oxygen
  and hydrogen atoms

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Charge is unevenly distributed. Water is a
polar molecule.
hydrogen bonds
Slight positive charge
Slight negative charge
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Hydrogen Bonds

• Hydrogen bonds the attraction between the
  hydrogen atom one water molecule and the oxygen
  atom on another water molecule

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• A property of water cohesion
• due to hydrogen bonds between water molecules

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• A property of water adhesion
• due to hydrogen bonds between water molecules
  and a different substance

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• Capillary action
• (due to adhesion)

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Mixture

• Two or more elements or compounds that are
  physically mixed but not chemically combined
  (salt and pepper)

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Solution
A solution of sodium chloride in water
Cl-
Na
salt crystal

• Solute the substance that is dissolved
• Solvent substance in which the solute dissolves
• Solution mixture in which all the components are
  evenly distributed

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• Dissolving salt in water

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Suspension

• A mixture of water and nondissolved material
  (example blood carries nondissolved particles
  and cells)

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Mixtures Solutions
and suspensions

• Mixture 2 or more elements or compounds that
  are physically mixed but not chemically combined
  (example sugar and sand)
• Solution mixture of 2 or more substances in
  which the molecules of the substances are evenly
  distributed
• Suspension mixture of fluid and nondissolved
  materials (example blood)

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pH

• H2O H
  OH-
• water hydrogen ion
  hydroxide ion
• In pure water, the number of hydrogen ions is
  equal to the number of hydroxide ions, so water
  is neutral
• If a solution has a higher concentration of H ,
  the solution is acidic
• If a solution has a higher concentration of OH-,
  the solution is basic

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Acids and bases and the pH Scale

• Acid a compound that forms H in solution
• Base a compound that forms OH- in solution
• The pH scale a measurement system that
  indicates concentration of H in solution
• Ranges from 0 to 14
• pH 7 . . . Solution is neutral
• pH lt 7 . . . Solution is acidic
• pH gt 7 . . . Solution is basic

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pH scale
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pH Scale

• Each step on pH scale represents a factor of 10
• A liter of solution with pH 4 has 10x as many H
  ions as a liter of solution with pH 5

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• Remainder of chapter presentations are in
  overhead transparency format. Not available as
  powerpoints.