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Chapter 2 - Chemistry

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  1. Chapter 2 - Chemistry Section 1: Composition of Matter

  2. Everything in the universe is made of matter Matter is anything that takes up space and has mass Matter

  3. Elements • Elements • pure substances that cannot be broken down chemically into simpler kinds of matter • There are 4 main elements that make up 90% of the mass of living things: • Oxygen – O • Carbon – C • Hydrogen – H • Nitrogen - N

  4. Elements Cont. • Each element has a chemical symbol

  5. Atomsare the simplest particle of an element. The properties of atoms determine the properties of the matter they compose Atomic Structure: Nucleus: the central region of an atom Made of protons (+) and neutrons (neutral) The number of protons in an element = the atomicnumber Electrons: have a negative charge that balances the protons Found in energylevels around the nucleus Each energy level can only hold a specific number of electrons Atoms

  6. Picture of Atomic Structure Energy Level Neutron Nucleus Proton Electron

  7. Compounds • Compounds • pure substances made of two or more elements • Shown in chemicalformulas • Ex: H2O  always 2H for 1O • The goal of making compounds is to fill the outermost energy level of an atom • Makes the atom more stable

  8. Compounds Cont. • Compounds are held together by bonds • Covalentbonds: two or more atoms share electrons • IonicBonds: electrons are transferred between atoms • Results in ions atoms with a full positive or negative charge

  9. Formation of a Covalent Bond

  10. Formation of an Ionic Bond

  11. Chapter 2 - Chemistry Section 2: Energy

  12. Energy and Matter • Energy • the ability to do work or cause change • Exists in various forms • Can convert one form of energy to another • Ex: Light Bulb • Electrical energy in the filament can be converted to radiant energy (light) and thermal energy (heat)

  13. Energy in Living Things • Forms of energy important to biological systems: • Chemical, thermal, electrical and mechanical • Freeenergy • the energy in a system available to do work • PotentialEnergy • the energy that matter stores due to position or location

  14. Three states of matter: Solids: have a fixed shape and volume Liquids: have a fixed volume, but will take the shape of whatever container it is in Gas: no fixed volume or shape Can change from state to state. Ex: H2O States of Matter

  15. Energy and Chemical Reactions • Chemical Reactions are the process through which chemical bonds are broken or made (and sometimes both!) 6H2O + 6CO2 + energy  C6H12O6 +6O2 Reactants: what you put in Products: what you get out

  16. ExergonicReactions: release energy to the environment EndergonicReactions: absorb energy from the envrionment Energy Transfer

  17. ActivationEnergy is the amount of energy that you need to start a reaction Catalysts reduce the amount of activation energy needed Enzymes are catalysts found in living things Activation Energy

  18. Reduction – Oxidation Reactions • RedoxReactions are reactions that transfer energy via the transfer of electrons between atoms • Oxidation: a reactant loses one or more electrons, becoming more positive • Reduction: a reaction gains one or more electrons, becoming more negative • Redox Reactions ALWAYS occur together! • LEO the lion goes GER • Ex: NaCl

  19. Chapter 2 - Chemistry Section 3: Solutions

  20. Describing Solutions • Solution: a mixture in which one or more substances are uniformly distributed in another substance • Solute: the substance dissolved in a solution • Solvent: the substance that does the dissolving • Concentration: measurement of the amount of solute in a fixed amount of solution • 2% salt = 2g of salt in enough water to make 100mL • SaturatedSolution: is a solution in which no more solute can dissolve • Aqueoussolution: solutions where water is the solvent

  21. Acids and Bases • Dissociation of Water • Water can dissociate (break apart) into two ions: • H20 H+ + OH- • The OH- is called the hydroxideion • The H+ can react with another water molecule: • H+ + H2O H3O+ • The H3O+ is called the hydroniumion

  22. Acids • When the concentration of hydronium ions is great than the concentration of hydroxide ions  the solution is acidic • Ex: HCl gas • HCl gas will dissolve in water in the following way: • HCl H+ + Cl- • The H+ will react with the water to create H3O+

  23. Bases • When the concentration of OH- is greater than H3O+ the solution is said to be basic • Ex: NaOH salt • NaOH salt will dissolve in water in the following way: • NaOH Na+ + OH- • The term alkaline refers to bases

  24. Compares the concentration of H3O+ to OH- in a solution Has a range from 0-14 0 = acid 7 = neutral 14 = base Based on a scale of 10 A pH of 4 means there are 10x more H3O+ ions than a solution with the pH of 5 pH Scale

  25. Buffers are chemical substances that neutralize small amounts of an acid or a base added to a solution Important for our body: Enzymes need specific pH ranges in order function correctly Buffers