The Chemistry of LifeThe Chemistry of Life

Unit 3Unit 3

Chapter 6Chapter 6

AtomAtom

ProtonProton: positively charged particles: positively charged particlesNeutronNeutron: no charge particles: no charge particlesElectronElectron: negatively charged particles: negatively charged particlesNucleusNucleus: area of the atom where protons : area of the atom where protons and neutrons are foundand neutrons are foundElectron cloudElectron cloud: area of the atom where : area of the atom where electrons are foundelectrons are found

Periodic table of elementsPeriodic table of elements

Element: substance that cannot be broken down to any simpler chemical substance

CompoundCompound

Chemical substance Chemical substance made up or two or made up or two or more atoms of more atoms of different elementsdifferent elements

Must be chemically Must be chemically combinedcombined

Ex: table salt (NaCl)Ex: table salt (NaCl)

Covalent bondCovalent bond: shared electrons : shared electrons between two atomsbetween two atoms

MoleculesMolecules: group of two or more atoms : group of two or more atoms joined covalentlyjoined covalently

How covalent bonds formHow covalent bonds form

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Ionic bondIonic bond: transferred electrons : transferred electrons between two atomsbetween two atoms

How ionic bonds are formedHow ionic bonds are formed

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Chemical reactionsChemical reactions

Process in which substances undergo Process in which substances undergo changechange

A + B A + B C + D C + D

– A and B are A and B are reactantsreactants.. means means yieldsyields..

– C and D are C and D are productsproducts..

MixtureMixture

combination of substances where the individual combination of substances where the individual substances retain their original characteristicssubstances retain their original characteristics

SolutionSolution

one or more substances (solute) is one or more substances (solute) is distributed evenly throughout another distributed evenly throughout another substance (solvent)substance (solvent)

                              

   

pHpH

measures the concentration of Hmeasures the concentration of H++ (protons) in a solution(protons) in a solution

Acid vs. BaseAcid vs. Base

AcidAcid: readily forms H: readily forms H++ when in water when in water– pH < 7pH < 7– Ex: stomach juicesEx: stomach juices

BaseBase: readily forms OH: readily forms OH-- when in water when in water– pH > 7pH > 7– Ex: urineEx: urine

NeutralNeutral pH = 7 pH = 7– Ex: bloodEx: blood

Properties of water: cohesionProperties of water: cohesion

PolarityPolarity: unequally shared electrons so : unequally shared electrons so that the molecule has unequal charge that the molecule has unequal charge distributiondistribution– Oxygen pulls on electrons more than Oxygen pulls on electrons more than

hydrogen, where oxygen becomes more hydrogen, where oxygen becomes more negative hydrogen becomes more positivenegative hydrogen becomes more positive

Polar covalent bonds lead to the Polar covalent bonds lead to the cohesioncohesion property of water where water molecules property of water where water molecules are attracted to other water molecules.are attracted to other water molecules.

Cohesion and hydrogen bondsCohesion and hydrogen bonds

Water resists temperature Water resists temperature change.change.

The bonds between oxygen and hydrogen The bonds between oxygen and hydrogen can absorb a large amount of heat energy can absorb a large amount of heat energy before they break.before they break.

Therefore, aqueous environments (ex: Therefore, aqueous environments (ex: lakes, oceans) where there may be great lakes, oceans) where there may be great changes in temperature, organisms can changes in temperature, organisms can still survive.still survive.

Water expands when it freezes.Water expands when it freezes.

Frozen water (ice) is less dense than liquid Frozen water (ice) is less dense than liquid water.water.

Water that is in the cracks of rocks can Water that is in the cracks of rocks can freeze and cause the cracks to become freeze and cause the cracks to become larger. Overtime, the rock erodes.larger. Overtime, the rock erodes.

Water as an ideal solvent.Water as an ideal solvent.

Many substances (solutes) can dissolve in Many substances (solutes) can dissolve in water.water.

Water readily crosses the cell membrane, Water readily crosses the cell membrane, and therefore substances that are soluble and therefore substances that are soluble in water can diffuse more easily.in water can diffuse more easily.

DiffusionDiffusion

The net movement of particles from an The net movement of particles from an area of higher concentration to an area of area of higher concentration to an area of lower concentrationlower concentration

Temperature and pressure can affect the Temperature and pressure can affect the rate (time) of diffusion.rate (time) of diffusion.

Diffusion animationDiffusion animation

PolymersPolymers: molecule made up of : molecule made up of many repeating unitsmany repeating units

“repeating” monkeys

Repeating glucose starch polymeranalogy Ex: glucose monomer bonded to form starch polymer

CarbohydratesCarbohydrates

Carbon, hydrogen, Carbon, hydrogen, and oxygen with a and oxygen with a ratio of Cratio of C1n1nHH2n2nOO1n1n

SEM image of cellulose fibers

LipidsLipids

Fats, oils, waxes, and Fats, oils, waxes, and steroid ringssteroid rings

ProteinsProteins

Carbon, hydrogen, oxygen, and nitrogen Carbon, hydrogen, oxygen, and nitrogen moleculesmolecules

Hemoglobin in red blood cells

Nucleic acidsNucleic acids

DNA, RNA, and ATP DNA, RNA, and ATP energy moleculeenergy molecule