CHAPTER 2

• THE CHEMICAL FOUNDATIONS OF THE CHEMICAL FOUNDATIONS OF LIFELIFE

• Alchemy and ChemistryAlchemy and Chemistry

WHAT IS MATTER?

• CHEMISTRYCHEMISTRY

• MATTER MATTER

• CHEMICAL REACTIONSCHEMICAL REACTIONS

• ATOMSATOMS

• NUCLEAR REACTIONSNUCLEAR REACTIONS

• MOLECULE MOLECULE

• COMPOUNDSCOMPOUNDS

What Is Chemistry?

metallurgymetallurgy

WHAT DETERMINES THE PROPERTIES OF AN ATOM?

MASSMASS

What Are Atoms Made Of?

Calculate molecular weight.Calculate molecular weight.

What Is the Internal Structure of an Atom?

• NUCLEUSNUCLEUS

• PROTONSPROTONS

• NEUTRONSNEUTRONS

• ELECTRONSELECTRONS

ISOTOPES

• RADIOACTIVE ISOTOPESRADIOACTIVE ISOTOPES

• HALF-LIFEHALF-LIFE

What Does Radioactivity Do to Living Organisms?

free radicalsfree radicals

Where Are the Electrons in an Atom?

• ENERGYENERGY• SHELLSSHELLS

• TWO RULES ON DISTRIBUTIONTWO RULES ON DISTRIBUTION• PRACTICE DRAWING COMMON ELEMENTSPRACTICE DRAWING COMMON ELEMENTS

WHAT HOLDS MOLECULES TOGETHER?

• Eight electrons to an energy levelEight electrons to an energy level

• 1,2, or 3 electrons may be given up1,2, or 3 electrons may be given up

• 4 electrons will usually be shared4 electrons will usually be shared

• 5,6, or 7 electrons may gain more5,6, or 7 electrons may gain more

• Inert elements have 8 electrons and are Inert elements have 8 electrons and are unreactiveunreactive

Covalent and ionic Bonds Are the Strong Interactions Among

Atomscovalent bondscovalent bonds

ionic bondsionic bonds

ionsions

Atoms Share Electrons in Covalent Bonds

• SPONCHSPONCH

• Organic compounds contain carbonOrganic compounds contain carbon

• Double covalent bondsDouble covalent bonds

• Triple covalent bondsTriple covalent bonds

What Determines the Shape of a Molecule?

Bonds give a 3-D structure.Bonds give a 3-D structure.

Fig. 2-8Fig. 2-8

How are radioisotopes useful?

Give examples.Give examples.

Atoms Lose and Gain Electrons in Ionic Bonds

Ions have a gain or loss of electrons Ions have a gain or loss of electrons to form + or - charges.to form + or - charges.

Opposite charges attract.Opposite charges attract.

Fig. 2-9Fig. 2-9

Atoms Have Different Tendencies To Gain or Lose

Electrons• Electronegativitity - Electronegativitity -

the tendency to gain the tendency to gain electronselectrons

• polar- has uneven charge polar- has uneven charge distributiondistribution

• nonpolar-has uniform nonpolar-has uniform charge distributioncharge distribution

Weak Interactions Also Hold Atoms Together

aqueous (watery) environmentaqueous (watery) environment

Hydrophobic Molecules Cling Together in an Aqueous Solution

Hydrophilic Hydrophilic

HydrophobicHydrophobic

Give examples.Give examples.

Van der Waals Attractions Reinforce Hydrophobic

Interactions

Hydrogen Bonds Are Weak But Important

Hydrogen bonds in water, protein, Hydrogen bonds in water, protein, and DNA. Fig. 2-12and DNA. Fig. 2-12

Water Is Denser as a Liquid Than as a Solid

• Table 2-2Table 2-2

• Compare water to alcohol and oilCompare water to alcohol and oil

Water Absorbs More Heat Than Most Substances

• Heat capacityHeat capacity • stores heatstores heat

• cools coasts and the bodycools coasts and the body

Water Molecules Cling to One Another

• CohesionCohesion

• Surface tensionSurface tension• Give examples.Give examples.

Water Molecules Cling to Many Other Substances

• AdhesionAdhesion

• Capillary actionCapillary action• Give examples.Give examples.

Water Is a Powerful Solvent

• SolventSolvent • SoluteSolute

• Amphipathic - contain both hydrophilic and Amphipathic - contain both hydrophilic and hydrophobic regionshydrophobic regions

• Examples- detergent and mayonnaiseExamples- detergent and mayonnaise• Fig. 2-18Fig. 2-18

Water Participates in Many Biochemical Reactions

Planet WaterPlanet Water

Water Molecules Continually Split into Hydrogen Ions and

Hydroxide IonsHydroxide ion (OH-)Hydroxide ion (OH-)

Hydronium ion (H3O+)Hydronium ion (H3O+)

Study equations.Study equations.

pH Scale

• pH = power of the pH = power of the hydrogenhydrogen

• pH scale 1 - 14pH scale 1 - 14• logarithm to the base logarithm to the base

10 10 • A pH of 2 is 100 X as A pH of 2 is 100 X as

strong as a pH of 4strong as a pH of 4• each number is a 10 each number is a 10

fold differencefold difference

• acid - a pH of 0-6.99acid - a pH of 0-6.99

• Contains more hydrogen Contains more hydrogen than hydroxide ionsthan hydroxide ions

• pH 7 = H + OH = H2OpH 7 = H + OH = H2O

• base - a pH over 7 - 14base - a pH over 7 - 14

• Contains more hydroxide Contains more hydroxide than hydrogen ionsthan hydrogen ions

• Fig. 2-20Fig. 2-20

Life At Low pH

Box 2-2Box 2-2

Why Is pH Important to Organisms?

Discuss examples.Discuss examples.

Buffers: How Do Organisms Resist Changes in pH?

• Buffers neutralize acids and bases.Buffers neutralize acids and bases.

• Carbonic acid and bicarbonate are two Carbonic acid and bicarbonate are two important buffers of the body.important buffers of the body.

• Body pH should be 7.35-7.45 or problems Body pH should be 7.35-7.45 or problems will occur.will occur.

• Acids and bases combine to form salts and Acids and bases combine to form salts and water.water.

• Acids buffer bases - bases buffer acidsAcids buffer bases - bases buffer acids