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The Chemical Context of Life
Unit 2 Chapter 2
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Matter Anything that takes up space and has mass Affected by gravity
Consists of elements and compounds
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Element Compound “pure” substance
Can’t be broken down to another substance Periodic table Compound 2 + different elements combined in a fixed ratio Ex. H2O, NaCl
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Elements of Life 20-25% essential elements
O, C, N, and H make up 96% living matter 4% : P, S, Ca, K & trace elements required in minute quantities (ex: Fe, I)
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Atoms and Molecules Atoms Mass Location Charge neutron 1 nucleus
Subatomic particles Mass (dalton or AMU) Location Charge neutron 1 nucleus proton +1 electron negligible shell -1
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Isotopes # neutrons varies, but same # of protons
Radioactive isotopes used as tracers (follow molecules, medical diagnosis) Uncontrolled exposure causes harm
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Strongest Bonds Ionic: 2 ions (+/-) bond (givers/takers) Na+Cl-
affected by environment
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Ionic bond
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Covalent: sharing of e-
Polar: covalent bond between atoms that differ in electronegativity Unequal sharing of electrons Nonpolar: e- shared equally O2 or H2
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Covalent bond
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Weaker Bonds Hydrogen: H of polar covalent molecule bonds to electronegative atom of other polar covalent molecules
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Bonds Covalent Ionic Hydrogen All important to life
Form cell’s molecules Quick reactions/ responses H bonds to other electronegative atoms Strong bond Weaker bond (esp. in H2O) Even weaker Made and broken by chemical reactions
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Function is related to shape
Similar shapes = mimic morphine, heroin, opiates mimic endorphin (euphoria, relieve pain)
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Chemical Reactions Reactants Products
6CO2 + 6H2O C6H12O6 + O2 Chemical equilibrium: point at which forward and reverse reactions offset one another exactly Reactions still occurring, but no net change in concentrations
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