Chemical Bonding

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Chemical Bonding

• Why do atoms form bonds?

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Atoms form bonds to become more
STABLE !
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How does an atom become stable?

• Atoms become stable by having their outer energy
  level filled with electrons
• This is accomplished by forming a bond with
  another atom

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Formation of Chemical Bonds

• Bonds are formed in the following ways
• Atoms can lose or gain electrons
• (results in an ionic bond)
• Atoms can share electrons (covalent bond)
• Compounds are formed as a result of these bonds

Formation of an ionic bond between sodium and
chlorine
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Organic Compounds (biomolecules)

• Compounds that contain carbon
• Hydrogen, oxygen, nitrogen, phosphorus and sulfur
  can also be found in organic compounds

A lipid (a.k.a. fat)
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Why Carbon?

• Carbon can form more bonds than any other element
  (4)
• This property allows carbon based molecules to be
  quite large and diverse

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Carbon Atom

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4 unpaired electrons 4 bonds formed
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Types of bonds
Single Bond (one pair of e- shared)
C
C
Double Bond (2 pairs of e- shared)
C
C
Triple Bond (3 pairs of e- shared)
C
C
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Types of Organic Compounds
Carbohydrates
Lipids (Fats)
Proteins
Nucleic Acids (DNA, RNA)
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Composition of Organic Compounds
Organic compounds are made of monomers -
individual subunits
Many monomers form polymers - larger molecules
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(No Transcript)
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Glycerol (monomer)
3 Fatty acids (monomers)
Lipid (polymer)
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Amino acid (monomer)
Amino acid (monomer)
Two amino acids bonded together (dipeptide -
polymer)
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Nucleic Acid (polymer)
Nucleotides (monomers)
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Nucleotide
Nitrogen base
Phosphate group
Five carbon sugar
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Types of biochemical reactions
Hydrolysis

• Breaking apart a polymer into smaller molecules
  (like monomers) by adding water (ex. digestion)

WATER
(See figure 6.18 on pg. 159 of your book)
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Types of biochemical reactions
Condensation

• combining two smaller molecules into a larger
  molecule by removing water

WATER
(See figure 6.18 on pg. 159 of your book)
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Enzymes

• protein molecules that regulate chemical
  reactions in the body

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Chemical Reactions
A

B
C

D
reactants
products
Atoms of reactant(s) are rearranged to form the
product(s)
Example of biochemical reaction Cellular
Respiration
C6H12O6 6 O2 6 CO2 6 H2O
glucose
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Enzymes act as Catalysts
Catalysts speed up chemical reactions without
being used up or changed during the reaction
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How do Enzymes Speed up Chemical Reactions?

• The energy required to get a chemical reaction
  started is the activation energy
• Enzymes work by lowering the activation energy to
  speed up the reaction

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enzymes
Active site - area of enzyme where reaction takes
place
End product (Example of hydrolysis reaction)
Enzyme-substrate complex
enzyme
Substrate (nutrient, drug, chemical, etc)
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Factors affecting the rate of a reaction

• Amount of enzyme present
• Amount of substrate present
• Temperature and pH

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Enzyme Denaturation
Enzyme is shown in yellow Blue molecules are the
substrate
Heat or pH change
No reaction occurs (active site is damaged and
substrate no longer fits)
Reaction takes place normally