1 unit 2: biomolecules, part 1 inorganic chemistry atomic structure and the periodic table bonds –...

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Unit 2: BIOMOLECULES, Part 1

INORGANIC CHEMISTRY

Atomic structure and the periodic table Bonds – ionic, covalent (and hydrogen) Solubility and polarity, electrolytic properties Properties of water, hydrogen bonding Acids, bases and buffers

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Atomic structure

Atomic number Atomic mass

Number of electrons Electron energy levels # valence electrons

Number of protons Number of protons +

number of neutrons (isotopes vary in #

neutrons)

Equal to # of protons Row on periodic table Group # (1-8) (active bonding

electrons)

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Bonds involve valence electrons

Metals tend to transfer electrons

Nonmetals tend to take electrons when bonding with metals

Nonmetals tend to share electrons when bonding to other non-metals

Ions: charged atoms due to the gain or loss of electrons

Ionic bonds: cations and anions

Covalent bonds: shared electrons

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Covalent and Ionic bonds

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Ionic bonds

Metals form cations when they lose valence electrons

Nonmetals form anions when they gain valence electrons

Generally are hydrophilic, dissolve in water, form electrolytes

Ionic equations show the ions into which they separate

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Covalent bonds

Shared electrons Non-metals to non-metals Do not form ions in solution May be polar or non-polar

covalent Covalent bonds are stronger

than ionic bonds CHNOPS compounds of

living things (“organic”) are covalently bonded

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H2O is a polar molecule, covalently bonded but with an unequal distribution of shared electrons

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Water is the “versatile solvent”

The hydrogen bondsbetween hydrogen and oxygen cause unique properties ofwater

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Polar solvents dissolve polar solutes

Sugar dissolves in water

Salt dissolves in water

Only ionic compounds form electrolytes in water

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Nonpolar solutes do not dissolve in polar solvents (water)

Salad oil

Oil

Gasoline

Vegetable shortening

butter

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Acids, Bases, Buffers

Acids release H+ in solution

Bases release OH- in solution

Buffers resist changes in pH

pHyrion paper

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pH scale

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Biological systems depend on buffers

Narrow tolerances to changes in pH

Acid rain alters pH of soils and aquatic ecosystems

Limestone is used as a buffer in acidified lakes