Science

• Chemical reaction


  A rearrangement of atoms in which some of the original bonds are broken and new bonds are formed to give different chemical structures

  
• In a chemical reaction, atoms are neither created, nor destroyed
• The Law of Conservation of Energy applies to chemical reactions
• Types of chemical reactions

  • Synthesis
  • Decomposition
  • Single Replacement
  • Double Replacement
  • Combustion
• Synthesis reaction


  Two or more elements or compounds combine to make a more complex substance
• Synthesis reaction


  • 2 Na + Cl2 → 2 NaCl
• Decomposition reaction


  Compounds break down into simpler substances
• Decomposition reaction

  • 2 H2O → 2 H2 + O2
• Single-replacement reaction


  Occurs when one element replaces another one in a compound

  
• Single-replacement reaction


  • FeCl2 + Cu → Fe + CuCl2

  MgBr2 + Cl2 → MgCl2 + Br2
• Double-replacement reaction


  Occurs when different atoms in two different compounds trade places
• Double-replacement reaction


  • AB + CD → AC + BD
• Combustion


  Requires a hydrocarbon and oxygen as reactants, produces CO2 and H2O as products
• Combustion reaction


  • CH4 + 2 O2 → CO2 + 2 H2O
• All combustion reactions must have a hydrocarbon and oxygen as reactants
• Reactions take place when particles collide
• Collision Theory


  In order for a reaction to occur: 1) Two reactants must collide 2) The collision must have enough energy
• Rate of reaction


  The speed at which a reaction occurs or how fast it occurs
• Reactions take place when particles collide with each other with a certain amount of energy
• Activation energy


  The minimum amount of energy needed for the particles to react, different for each reaction
• Factors that affect the rate of reactions


  • temperature
  • concentration of dissolved reactants
  • pressure of gaseous reactants
  • surface area of solid reactants
  • use of a catalyst or enzyme
• Temperature


  • The higher the temperature, the faster the rate of a reaction
  • At a higher temperature, particles have more energy and are more likely to collide with other particles
• Concentration


  • The higher the concentration of a dissolved reactant, the faster the rate of a reaction
  • Higher concentration means more particles in the same volume, increasing collisions
• Pressure


  • Increasing the pressure of gaseous reactants increases the rate of reaction
  • Higher pressure means the gas particles are in a smaller space, increasing collisions
• Surface area


  • A larger surface area increases the rate of reaction
  • More surface area means more area for reactant particles to collide with
• Catalysts


  • Catalysts change the rate of a reaction without being used up
  • Most catalysts lower the reaction's activation energy
• Catalysts are substances that change the rate of a reaction without being used up in the reaction
• What are the 4 biomolecules?


  • Carbohydrates
  • Lipids
  • Nucleic Acids
  • Proteins
• WE TYPICALLY GET BIOMOLECULES FROM FOOD… THIS IS WHY WE MUST EAT IN THE FIRST PLACE!
• THE BIOMOLECULES SERVE TO KEEP ORGANISMS ALIVE.
• Carbohydrates


  ARE SUGARS!
• We get 4 kilocalories per gram of carb that we eat!
• Carbohydrates


  • Most common organic molecule
  • Function: Primary energy source our body needs
  • Elements present: C, H, O (1:2:1 ratio)
• Monomer (building block)


  Monosaccharides (Glucose is most common)
• Polymer


  Polysaccharides (starch, Glycogen, Cellulose, Chitin)
• Examples of Carbohydrates


  • Chocolate, Bread, Pasta, Fruits, Vegetables (ALL FROM PLANTS!!!)
• Sugars that make up Carbs


  • Single sugar: monosaccharide (e.g. glucose, fructose)
  • 2 monosaccharides: disaccharide (e.g. maltose, sucrose)
  • 3+ monosaccharides: polysaccharide (e.g. Starch, Glycogen, Cellulose, Chitin)
• Starch


  Used for energy storage in plants, Potatoes, pasta and rice are starches, They provide a quick form of energy for the body
• Glycogen


  Used for energy storage in animals, Formed in the Liver
• Cellulose


  • Provides structural support in plants (found in the cell wall)
  • Gives us fiber!