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Chapter 2 - Chemistry

Chapter 2 - Chemistry. Section 1: Composition of Matter. Everything in the universe is made of matter Matter is anything that takes up space and has mass. Matter. Elements. Elements pure substances that cannot be broken down chemically into simpler kinds of matter

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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

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