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Chemistry Review

Chemistry Review. Atom Anatomy. Basic unique structure of matter Protons: positive, atomic number Neutrons: no charge, atomic mass = protons + neutrons, isotope = when number of neutrons change and mass changes

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Chemistry Review

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  1. Chemistry Review

  2. Atom Anatomy • Basic unique structure of matter • Protons: positive, atomic number • Neutrons: no charge, atomic mass = protons + neutrons, isotope = when number of neutrons change and mass changes • Electrons: in neutral atom protons = electrons, ion = adding or removing electrons, positive ion = lost electrons, negative ion = gained electrons

  3. ISOTOPES: Same protons same electrons different neutrons Atomic mass changes IONS: Only electrons change Charge ≠ neutral + ion = lost electrons - Ion = gained electrons

  4. Most Abundant Elements in the Body • C (18.5%) H ( 9.5%) O (65%) • N (3.2%) P (1.0%) S ( .25%) Ca (1.5%) • Mg (.1%) Na (.2%) Cl (.2%) K (.35%) • Fe (.005%) • Trace elements (.2% all together). Examples are Cu, Cr, B, Mn, Se and others. • We are organic (carbon based)

  5. Combining Atoms • Molecule: 2 or more atoms combined by covalent or ionic bonds • Covalent bond: formed by sharing of valence electrons. Biologically stable. Carbon involved – can form single, double, or triple bonds • Ionic bond: formed by (+) and (-) ions attracted to each other. Total (+) charge must = and cancel total (-) charge. Ionic compounds are referred to as electrolytes • Free Radical: electrically charged particle (usually involving oxygen with extra charge). Reactive, unstable, destructive. Antioxidants (carotenes, Vit. C, Vit. E) protect body from free radicals by destroying/blocking free radicals. Aging???

  6. Covalent molecule: Valence electrons shared within overlapping electron cloud. Notice every electron has a partner. Octet = 8 total electrons for each atom Ionic compound: not really a molecule but repeating (+)(-) arrangement of ions held together like a magnet. Most ionic compounds dissolve easily in water and because ions separate in water, they conduct electricity (electrolytes) (+) ion lost electrons = cation (-) ion gained electrons = anion

  7. Covalent Bond – More Details • Sometimes electron sharing is equal between atoms = NONPOLAR BOND and MOLECULE • Sometimes electron sharing between atoms isn’t equal. Electrons pulled more to one side of bond. Molecule “acts” like it’s made of ions, even though no ions are present = POLAR BOND and MOLECULE • 2 Atoms can form multiple bonds. Double bond = 2 electron pairs shared (4 total electrons). Triple bond = 3 electron pairs (6 total electrons) • Multiple bonds aren’t as stable as single bonds

  8. Multiple Bonds Comparison of Nonpolar bonds, Polar bonds, and ionic bonds

  9. Hydrogen Bonds • Special type of polar covalent bond • Hydrogen “acts” like it’s positive because it’s not as strong an electron attractor as Oxygen or Nitrogen (who “act” negative) • Still no ions, just not 100% equal sharing • Easily broken, easily formed • H bonds form links between different parts of large molecules, like in DNA

  10. Hydrogen bonds in DNA link Guanine side to Cytosine side. Note how H is attracted to both O and N

  11. Chemical Reactions • Happen when reactant (what you start with) chemical bonds break apart to form products (what you end with) with new chemical bonds • Energy always involved in chemical reactions. Potentialenergy is contained within the reactant bonds. When these bonds are broken, PE is converted into kineticenergy (motion) and heatenergy as well as a new source of potential energy in the new chemical bonds of the products.

  12. Types of Chemical Reactions • Synthesis: 2 or more small atoms and/or molecules combine to form 1 larger molecule Example: 2 H2O + O2 → 2H2O • Decomposition: reverse of synthesis; 1 larger molecule breaks apart into 2 or more smaller atoms and/or molecules Example: 2 K(ClO3) → 2KCl + 3 O2

  13. Types of Chemical Reactions • Exchange (ionic): ionic compounds break apart and rearrange into new combinations (but still maintain +/- rules) Example: NaCl + Ag(NO3) → Na(NO3) + AgCl • Reversible: reactions that can go forward and backward under different conditions (usually indicated on the arrow). Acid/base balancing reactions are an example. Example: HCl + NaOH ↔ HOH + NaCl

  14. Types of Chemical Reactions • Dehydration: the joining of 2 large molecules through the removal of water (OH from 1 molecule and H from the other). Products are a much larger molecule and HOH (water) • Hydrolysis: hydro (water) lysis (break). Water reacting with larger molecule to break larger molecule (and ultimately water) apart. The reverse of dehydration.

  15. HYDROLYSIS DEHYDRATION

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