Bio NOTES: Intro to the Chemistry

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Bio NOTES Intro to the Chemistry
Your life DEPENDS on chemistry!

1. When you inhale oxygen, your body uses it in
   chemical reactions!

1. When you eat food, your body breaks it down and
   uses it in chemical reactions!

All living things are made up of chemical
compounds

• A compound is made of atoms of different
• elements bonded together, such as H2O or CO2
• These compounds are the building
• blocks of our body and the world around us.
• The bonds that can hold compounds together
• are ionic, covalent, and hydrogen bonds.

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3 Types of Bonds
1. Ionic bond forms between oppositely
charged ions

• Ion atom that has lost or
• gained electrons

2. Covalent bond forms when atoms share a
pair of electrons
3. Hydrogen bond forms between slightly
positive hydrogen atoms and slightly
negative atoms
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WATER

• Water is a polar molecule
• polar has slightly charged regions
• nonpolar does not have charged regions
• Oxygennegative charge
• HydrogenPositive charge
• 2. Water LOVES itself, therefore it clings to
  itself!
• -This is called Cohesion
• - this creates Surface Tension
• Water also loves other substances!
• -This is called adhesion
• -This causes capillary action

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3. Water is held together by hydrogen bonds
Negative Oxygen end of one water molecule is
attracted to the Positive Hydrogen end of another
water molecule to form a HYDROGEN BOND
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WATER
4. Many compounds dissolve in water. Water is a
universal Solvent

• A solution is formed when one
• substance dissolves in another.
• - A solvent dissolves other substances.
• A solute dissolves in a solvent

water loving
hydrophilic hydrophobic
water fearing
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Water is Less Dense as a Solid

• Ice is less dense as a solid than as a liquid
  (ice floats)
• Liquid water has hydrogen bonds that are
  constantly being broken and reformed.
• Frozen water forms a crystal-like lattice whereby
  molecules are set at fixed distances.

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• Water is Less Dense as a Solid
• Which is ice and which is water?

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• Water is Less Dense as a Solid

Water
Ice
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• Properties of Water Flapbook
• Fold a sheet of paper hot dog or landscape
  style.
• Divide the sheet of paper into four equal
  sections.
• Label each section as follows Solvent, cohesion,
  polar molecule, density
• Then cut each segment (top only to form flaps).
• Under each flap include the following information
  for each unusual property of water
• Meaning of the term
• Examples of why this property of water is
  important to life
• Picture of this property in nature

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pH

• Reminder Water molecules are held together by
  ___________________ bonds.
• These are relatively __________ bonds.
• These bonds are constantly _________ and
  _____________.
• When water breaks apart, there is a way to
  represent this using chemical equations.
  (Dissociation of water)

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Acids, Bases and pH

• water molecules dissociates into a Hydrogen Ion
  (H) and a Hydroxide Ion (OH-)
• Hydrogen Ion
  Hydroxide Ion
• Acid Base

H2O ? H OH-
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The pH Scale
Some compounds form acids or bases

• An acid releases a hydrogen ion when it
  dissolves in water.
• - high H concentration
• - pH less than 7

• A base removes hydrogen ions from a solution

- low H concentration - pH greater than 7

• A neutral solution has a pH of 7

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A B
Left to right
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