AP Biology Summer Reading

Chapter 2

Chapter 3

Chapter 4

Chemical Context of Life

Matter- how would you define it???

Element/CompoundsWhat’s the

difference?

Chemical Context of LifeThe atom- composed of:Atomic number:Mass number:Isotopes:Radioactive isotopes: Atomic notation:

Chemical Context of Life

Energy (definition from physics):Energy levels:How many energy levels are found

on the periodic table:Valence electrons:

Chemical Bonding

Covalent Double covalent Nonpolar covalentPolar covalentIonicHydrogenvan der Waals

Covalent Bonding

Sharing pair of valence electrons

Number of electrons required to complete an atom’s valence shell determines how many bonds will form

Ex: Hydrogen & oxygen bonding in water; methane

Polar/nonpolar covalent bonds

Electronegativityattraction for electrons

Nonpolar covalent •electrons shared

equally •Ex: diatomic H and O

Polar covalent•one atom more electronegative than the other (charged)•Ex: water

Polar/nonpolar bonds

Ionic bonding

High electronegativity difference strips valence electrons away from another atom

Electron transfer creates ions (charged atoms)

Cation (positive ion); anion (negative ion)

Ex: Salts (sodium chloride)

Hydrogen bonds

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

van der Waals interactions

Weak interactions between molecules or parts of molecules that are brought about by localized charge fluctuations

Due 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?

Creates environment suitable for lifeNecessary for many biological and

chemical processes

Water as a polar molecule:

Polar- opposite ends, opposite charges

Oxygen is more electronegative than hydrogen Partial charges result

Gives water many distinct properties

Properties of Water:

Cohesion- H+ bonds holding molecules together

Adhesion- H+ bonds holding molecules to another substance

Examples: water transportation in plants- flowing against the force of gravity (adhesion also)

Properties of Water:Surface tension- measurement

of the difficulty to break or stretch the surface of a liquid

Gives rain drops their tear- drop shape

Result of Cohesion

Properties of Water:Water has a relatively high

specific heat capacity Specific heat- amount of

heat required to raise the temperature of 1g. of a substance 10C.

Hydrogen bonds contribute to this property

Properties of Water:Heat of vaporization-

quantity of heat required to convert 1g from liquid to gas states

Why is this important?

Density

Water is a dense substance: D= 1g/mL

Due to hydrogen bondingAt what temperature is

water its most dense? What happens to the

density as water approaches 00C?

Acid/Base & pH

Dissociation of water into a hydrogen ion and a hydroxide ion

Acid: increases the hydrogen concentration of a solution

Base: reduces the hydrogen ion concentration of a solution

pH: “power of hydrogen” Buffers: substances that

minimize H+ and OH- concentrations (accepts or donates H+ ions)

Organic chemistry

Biological thought: Vitalism (life force outside physical

& chemical laws) Berzelius Mechanism (all natural

phenomena are governed by physical & chemical laws) Miller

Carbontetravalencetetrahedronshape determines function

PCA:

The molar mass of table sugar is ???(C12H22O11)

How would you make a sugar water solution with a 1M concentration?

Organic Chemistry:

Carbon based molecules Tetravalence- carbon has four

valance electrons (4 covalent bonds)

High energy storageDiverse Molecules:

hydrocarbons

Isomers:

same molecular formula, but different structure & properties

Isomers:

Structural-differing covalent bonding

arrangement (straight vs. branched)

Geometric-differing spatial arrangement

Enantiomers-mirror images pharmacological industry

Functional Groups, I

Attachments that replace one or more of the hydrogen bonded to the carbon skeleton of the hydrocarbon

Each has a unique property from one organic compound to another

Functional Groups:

Hydroxyl Group (-OH): oxygen bonded to hydrogen Alcohols Polar

Functional Groups:

Carbonyl (C=O): carbon atom double bonded to oxygen Keytones and Aldehydes Polar

Functional Groups:

Carboxyl Group (O=C-OH): oxygen double bonded to carbon bonded to a hydroxyl Polar Releases H+ ion- forms acids

Functional Groups:

Amino Group (-NH2): nitrogen bonded to two hydrogen (Amino acids also contain carboxylic acids)

amines acts as base

Functional Groups, II

Sulfhydryl Group (-SH): sulfur bonded to H thiols

Functional Groups:

Phosphate Group (-PO42-):

phosphate ion one oxygen is bonded to a carbon

skeleton polar