CHAPTER TWO

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CHAPTER TWO

• The Chemical Basis of Life

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2.1 Rattlebox Moth (Utetheisa ornatrix)

• Caterpillar feeds on rattlebox, sweet clover, and
  obtains a poison.

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The foul-tasting chemical froths out when the
moth is disturbed
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Cornell Biologists Eisner Gang

• Male moth's sperm package includes 'life
  assurance policy,' to his freshly mated female

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• protects her for life against predatory spiders.
• This moth was released after the spider tasted
  it

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Safe Sex For Moths

• Yeah, mating takes 8-9 hours, so the last thing
  you want is a predator interrupting you.

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• A female will have up to 20 mates in her 30-day
  lifespan.

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Scent of male perspirationregulates ovulation
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Chemical Element

• A substance that cannot be broken down to other
  substances by ordinary chemical means
  
• Abbreviation
• symbol

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Element Song

• Tom Lehrer's "The Elements". A Flash animation by
  Mike Stanfill, Private Hand
  
• Sing along with the handout

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Elements are Found on
Periodic Table
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You will need to know for the QUIZ!

• -how to spell correctly
• -correctly write the symbols
• (capital letter, second letter is lower case)
• For all the elements on the chart on p. 19
• (INCLUDING TRACE ELEMENTS)

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Trace Elements

• Needed by some organisms but only in very small
  amounts
  
• Like iodine, we need only 0.15 mg per day
• A deficiency will cause a goiter

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Compound

• A substance containing 2 or more elements in a
  fixed ratio
  
• EX NaCl sodium chloride
• H2SO4 sulfuric acid
• H2O water

subscripts
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Atom

• Smallest unit of matter that still retains the
  properties of an element
  
• EX every atom in a gold block looks like all the
  other gold atoms

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SUBATOMIC PARTICLES
nucleus
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ION

• Atom or molecule with an electrical charge () or
  (-)
  
• Due to the gain or loss of electrons
• Overhead-Line Spectra (CLICK HERE)

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Which are ions?

• Cl O-2 Ca1 N2
  Why?
  
• O-2 Ca1 Charged atoms, show charges as
  superscripts

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What do we call the forces that

• Hold atoms together in a molecule?
• Chemical bondsnot to be confused with James Bond

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IONIC BOND

• What makes up ionic bonds?
• IONS
• WHY?
• Opposite charged ions attract
• Atomic Bonding (click on sodium chloride link)
• Ionic Bonds (another link)

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Chemical Reaction

• Chemical Bonding (click on animation)

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Covalent Bond

• What makes up covalent bonds?
• Atoms that are sharing electrons
• Atomic Bonding (click on water link below)
• Covalent Bonds (another link)

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Do you know these chemical terms?

• Element
• Compound
• Symbol
• Formula
• Atom
• Molecule

• One kind of atom (Na, H)
• 2 or more different kinds of elements chemically
  joined (NaCl, H2O)
  
• Abbreviation of an element (Si, C)
• Abbreviation of a compound (Na2S)
• 1 unit (H, Na, Cl)
• 2 or more atoms chemically joined (same or
  different H2, NaCl)
  

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Need More?

• Tutorial 2.1 Chemical Bond Formation (Click on
  animation)
  
• Chem4Kids.com Atomic Structure Quiz (try your
  skills!)