Chemistry of water (2.3) and Acid and Bases (2.4)

• A chemical reaction is the process of...

  making or breaking a bond
• What is an example of a chemical reaction with bread?

  Eating bread as the saliva is breaking chemical bonds
• What is the definition of metabolism in biology?

  All the chemical reactions in a cell or organism
• How do covalent bonds form?

  When two atoms share electrons
• What are the two types of covalent bonds?

  Polar and nonpolar
• What is a nonpolar covalent?

  equal sharing of electrons (ex: methane)
• What is a polar covalent?

  Unequal sharing of electrons (ex: H2O)
• Do most biomolecules contain polar or nonpolar covalent bonds?

  Polar
• What element do polar bonds often have?

  oxygen
• What is electronegativity?

  the ability of an atom to attract electrons towards itself
• What element is the most electronegative?

  oxygen
• What is Nitrogen's level of electronegativity?

  slightly electronegativity
• What does it mean that Carbon and Hydrogen are electropositive?

  easier to give away electrons
• What can polar molecules make?

  hydrogen bonds with other polar molecules
• What are hydrogen bonds?

  weak attraction between a slightly positive hydrogen atom and a slightly negative atom
• Polar covalent bonds lead to ___ and then lead to ___ and then lead to ___

  hydrogen bonds, surface tension/capillary reaction/evaporating cooling (sweating)
• Is a single hydrogen bond weak or strong?

  Weak
• Are multiple hydrogen bonds weak or strong

  strong
• What chemical characteristics does water have due to hydrogen bonds?

  cohesive/adhesive, molecules dissolving, absorb much energy, ice is less dense than liquid water
• Why is water "sticky"

  hydrogen bonds
• What are enzymes?

  proteins
• What are exoskeletons made out of?

  chitin
• Where are neutrons and protons located?

  Nucleus
• What is the definition of cohesion?

  water molecules hydrogen bonding to other water molecules
• What does cohesion lead to?

  surface tension
• What is the definition of adhesion?

  Water molecules hydrogen bonding to other polar surfaces
• How does water move through plants?

  capillary action
• What is capillary action?

  the combination of adhesion and cohesion
• What is evaporative cooling (sweating)

  As water evaporates, it pulls heat from the organism
• What bonds must be broken to evaporate?

  Hydrogen
• What is the pH scale?

  measures acidity or alkalinity of a liquid
• Why is pH important in biology?

  impacts biochemical reactions
• Organisms change ___ of different parts of their --- to manipulate ---.

  pH

  body

  chemistry
• pH scale: 0-7

  acidic (positive protons, hydrogen ion, H+)
• pH scale: 7

  neutral
• pH scale: 7-14

  Basic (Alkaline) (negative hydroxyl ions, -OH)
• pH varies in ___ and ___

  body

  temperature
• What keeps pH constant?

  Buffers
• What is the definition of buffer?

  chemicals that keeps pH within normal limits (homeostasis)
• What are three built-in mechanisms does the human body to prevent pH changes?

  kidney, lungs, buffers