The Chemistry of Life

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The Chemistry of Life
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• In your notebooks
• Todays date
• Title Unit The Chemistry of Life
• With a partner, think about this question Why is
  chemistry important in biology? Make a list of 3
  ways chemistry affects living things and/or
  chemical processes living things perform.

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The Chemistry of Life

• Big Idea Matter and Energy
• Essential question What are the basic chemical
  principles that affect living things?
• Guiding questions
• What is the matter in organisms made of?
• Why are the properties of water important to
  organisms?
• How do organisms use different types of carbon
  compounds?
• How do chemicals combine and break apart inside
  living organisms?

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Basic Chemistry

• Atoms are the basic unit of matter
• Elements are pure substances which consist of
  entirely one type of atom
• Molecules and compounds are formed when elements
  bond together
• All things (living and nonliving) on Earth are
  composed of atoms, molecules, and compounds

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Subatomic Particles What makes up an
atom?Electrons, Protons, Neutrons

• The number of protons () determines chemical
  behavior
• The number of electrons (-) determines how it
  will react with other atoms
• The number of neutrons (no charge) determines
  radioactivity (isotopes)

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Element, molecule, or compound?

1. Ca (calcium)
2. OH- (hydroxide ion)
3. O2 (oxygen)
4. H20 (water)
5. C6H12O6 (glucose)
6. Are these examples of living things?

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Elements of Life

• Carbon
• Hydrogen
• Nitrogen
• Oxygen
• Phosphorus
• Sulfur
• Chlorine Cl
• Potassium K
• Calcium
• Sodium Na

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Ions

• When an atom gains or loses an electron it also
  gains a charge ( if loses an electron) or (- if
  gains an electron)
• When an atom or groups of atoms has a () or (-)
  charge it is called an ion
• Our heartbeat, taste, and nervous systems all
  utilize ions to function

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• How do elements form the molecules and compounds
  of life?

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Types of Bonding Covalent Bonds

• Covalent bonds
• When two atoms share electrons equally
• The electrons move around the nucleus of both
  atoms in the bond
• Examples
• H2
• O2
• H20

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Types of Bonds Ionic Bonds

• Formed when electrons are transferred from one
  atom to another one atom gains e- and one atoms
  loses e-

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Bonding
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Chemical Formulas

• The chemical formula of a substance indicates
• The elements in the molecule
• The number of atoms of each element in the
  substance
• Example 6H2S04
• 2 atoms of the element hydrogen 1 atom of the
  element sulfur 4 atoms of the element oxygen
• A number in front of substance indicates how many
  molecules of that substance there are
• There are 6 molecules of H2S04 in the example

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Chemical Reactions

• Are changes which result in the formation of one
  or more new substances
• The starting materials are called the reactants
  (what is reacting)
• The ending materials are called products (what is
  being produced)

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Chemical Reactions

• During chemical reaction bonds between molecules
  can be broken (not always) and new bonds are
  formed
• Example A B ? C
• Bond between A and B forms new compound C
• Example AB CD ? AC BD
• Bond between A and B broken
• Bond between C and D broken
• Bond between A and C forms
• Bond between B and D forms

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Chemical Reactions
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Chemical Equations

• Identify the reactants and products of a chemical
  reaction
• Gives the chemical formula of each substance
  involved in the reaction (the reactants and the
  products)
• Looks like this
• X Y ? XY
• AB CD ? AC BD
• Reactants on LEFT of arrow
• Products on RIGHT of arrow

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Water

• Essential to life processes
• Transport materials
• Molecules can dissolve in it and react

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Polar Molecule

• Sometimes when atoms form covalent bonds, they do
  not share electrons equally
• There is an unequal distribution of charge (since
  electrons have a negative charge)
• In other words, one side of the molecule is
  positive and the other side of the SAME
  molecule is negative

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Polar Molecule H20
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Polar Molecule H20

• For a water molecule, the negative side is the
  Oxygen and the positive side in the Hydrogen (the
  ears)

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Non-Polar Molecule

• A non-polar molecule is one that the electrons
  are distributed more equally
• There is NO negative or positive side

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Non-Polar Molecule CO2
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Hydrogen Bonding

• The positive side of one water molecule is
  attracted to the negative side of another water
  molecule
• These bonds are weak
• Attract water molecules to each other

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Hydrogen Bonding of Water
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Hydrogen Bonding of Water

• No electrons are actually shared between water
  molecules
• Hydrogen bonds weaker than covalent bonds easily
  break and form again

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Cohesion

• The tendency of like molecules to be attracted
  to one another
• Molecules stick to each other

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Surface Tension A Special Type of Cohesion

• Surface tension due to cohesion of water
• Cohesion of the top layer of the water

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Adhesion

• The sticking together of molecules of different
  substances
• Examples water adhering to paper, plastic, or
  glass