AP Biology Summer Reading zChapter 2 zChapter 3 zChapter 4

Chemical Context of Life zMatter- how would you define it??? zElement/Compounds zWhat’s the difference?

Chemical Context of Life zThe atom- composed of: zAtomic number: zMass number: zIsotopes: zRadioactive isotopes: zAtomic notation:

Chemical Context of Life zEnergy (definition from physics): zEnergy levels: zHow many energy levels are found on the periodic table: zValence electrons:

Chemical Bonding zCovalent zDouble covalent zNonpolar covalent zPolar covalent zIonic zHydrogen zvan der Waals

Covalent Bonding zSharing pair of valence electrons zNumber of electrons required to complete an atom’s valence shell determines how many bonds will form zEx: Hydrogen & oxygen bonding in water; methane

Polar/nonpolar covalent bonds zElectronegativity attraction for electrons zNonpolar covalent electrons shared equally Ex: diatomic H and O zPolar covalent one atom more electronegative than the other (charged) Ex: water

Polar/nonpolar bonds

Ionic bonding zHigh electronegativity difference strips valence electrons away from another atom zElectron transfer creates ions (charged atoms) zCation (positive ion); anion (negative ion) zEx: Salts (sodium chloride)

Hydrogen bonds zHydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom (oxygen or nitrogen)

van der Waals interactions zWeak interactions between molecules or parts of molecules that are brought about by localized charge fluctuations zDue to the fact that electrons are constantly in motion and at any given instant, ever-changing “hot spots” of negative or positive charge may develop

Water: Why is it important? zCreates environment suitable for life zNecessary for many biological and chemical processes

Water as a polar molecule: zPolar- opposite ends, opposite charges zOxygen is more electronegative than hydrogen yPartial charges result zGives water many distinct properties

Properties of Water: zCohesion- H+ bonds holding molecules together zAdhesion- H+ bonds holding molecules to another substance zExamples: water transportation in plants- flowing against the force of gravity (adhesion also)

Properties of Water: zSurface tension- measurement of the difficulty to break or stretch the surface of a liquid zGives rain drops their tear- drop shape zResult of Cohesion

Properties of Water: zWater has a relatively high specific heat capacity ySpecific heat- amount of heat required to raise the temperature of 1g. of a substance 1 0 C. yHydrogen bonds contribute to this property

Properties of Water: zHeat of vaporization- quantity of heat required to convert 1g from liquid to gas states zWhy is this important?

Density zWater is a dense substance: D= 1g/mL zDue to hydrogen bonding zAt what temperature is water its most dense? zWhat happens to the density as water approaches 0 0 C?

Acid/Base & pH zDissociation of water into a hydrogen ion and a hydroxide ion zAcid: increases the hydrogen concentration of a solution zBase: reduces the hydrogen ion concentration of a solution zpH: “power of hydrogen” zBuffers: substances that minimize H+ and OH- concentrations (accepts or donates H+ ions)

Organic chemistry zBiological thought: zVitalism (life force outside physical & chemical laws) Berzelius zMechanism (all natural phenomena are governed by physical & chemical laws) Miller zCarbon tetravalence tetrahedron shape determines function

PCA: zThe molar mass of table sugar is ??? z(C 12 H 22 O 11 ) zHow would you make a sugar water solution with a 1M concentration?

Organic Chemistry: zCarbon based molecules yTetravalence- carbon has four valance electrons (4 covalent bonds) zHigh energy storage zDiverse Molecules: yhydrocarbons

Isomers: zsame molecular formula, but different structure & properties

Isomers: zStructural- differing covalent bonding arrangement (straight vs. branched) zGeometric-differing spatial arrangement zEnantiomers-mirror images pharmacological industry

Functional Groups, I zAttachments that replace one or more of the hydrogen bonded to the carbon skeleton of the hydrocarbon zEach has a unique property from one organic compound to another

Functional Groups: zHydroxyl Group (-OH): oxygen bonded to hydrogen yAlcohols yPolar

Functional Groups: zCarbonyl (C=O): carbon atom double bonded to oxygen yKeytones and Aldehydes yPolar

Functional Groups: zCarboxyl Group (O=C-OH): oxygen double bonded to carbon bonded to a hydroxyl yPolar yReleases H+ ion- forms acids

Functional Groups: zAmino Group (-NH 2 ): nitrogen bonded to two hydrogen (Amino acids also contain carboxylic acids) y amines yacts as base

Functional Groups, II zSulfhydryl Group (-SH): sulfur bonded to H ythiols z

Functional Groups: zPhosphate Group (-PO 4 2- ): y phosphate ion yone oxygen is bonded to a carbon skeleton ypolar