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Atoms vs Molecules
• Smallest unit of matter is the Atom or the Molecule– Atoms have only 1
element– Molecules have more
than 1 kind of element joined together chemically
Periodic Table of the Elements
• Single type of atom
• 92 naturally occurring, humans have made a few more
Atomic Symbols
• 1 or 2 letters representing the atom– C – Carbon– H – Hydrogen– O – Oxygen– N – Nitrogen
• Most commonly occurring elements in Biology!
Molecule
• Various types of atoms joined together to make a substance that does not resemble the two elements
• Hydrogen – gas• Oxygen – gas• Water - liquid
Representing Molecules
• Chemical Formula use chemical symbols and numbers to represent a compound
H2O
• Structural Formula uses chemical symbols and lines to represent
a compound
Chemical Bonds
• Atoms combine to form molecules by sharing or trading electrons and forming links between them.
Bonding
• Chemical bonds are very stable– Forming a bond
stores energy
– Breaking a bond releases energy
KEY IDEA!!!
Octet Rule
• The number of bonds depends on the number of electrons in the valence (outermost) shell
• Valence Electrons = Those electrons in the outermost shell/ring of the atom
• All atoms like to form an octet (exception of Hydrogen,which likes 2)
Octet Rule Practice Element # Valence
Electrons# needed? # bonds?
Carbon 4
Hydrogen 1
Oxygen 6
Nitrogen 5
Organic Vs Inorganic Molecules
• Organic Molecules – occur in living things• Generally larger and more complicated in
shape than inorganic molecules
• Always have Carbon & Hydrogen• Usually have Oxygen• Sometimes have Nitrogen
CHON
Four types of Organic Molecules
Type Use Look For
Parts Found
Protein
Carbohydrate
Lipid
Nucleic Acid
Four types of Organic Molecules
Type Use Look For
Parts Found
Protein Building block
Nitrogen Amino acid Meats
Carbohydrate
Lipid
Nucleic Acid
Four types of Organic Molecules
Type Use Look For
Parts Found
Protein Building block
Nitrogen Amino acid Meats
Carbohydrate Energy 5/6 carbon ring
Glucose Sugar/ starch
Lipid
Nucleic Acid
Four types of Organic Molecules
Type Use Look For
Parts Found
Protein Building block
Nitrogen Amino acid Meats
Carbohydrate Energy 5/6 carbon ring
Glucose Sugar/ starch
Lipid Cell Membrane, Organ protection Energy Storage
“E” shape Glycerol and Fatty Acids
Fats/ waxes
Nucleic Acid
Four types of Organic Molecules
Type Use Look For
Parts Found
Protein Building block
Nitrogen Amino acid Meats
Carbohydrate Energy 5/6 carbon ring
Glucose Sugar/ starch
Lipid Cell Membrane, Organ protection Energy Storage
“E” shape Glycerol and Fatty Acids
Fats/ waxes
Nucleic Acid Information Storage “blueprints”
3 parts Phosphate, 5 carbon sugar and nitrogen base
DNA
Monomer vs Polymer
Monomer (Single Unit) Polymer (Long Chain)
Amino Acid Polypeptide or Protein
Carbohydrate Disaccharide, Trisaccharide, Polysaccharide or Starch
• Dehydration Synthesis– Remove water to form long chains
• Simple sugars into starches
• Hydrolysis– Add water to break chains
• Polysaccharides into monosaccharides