CHAPTER 6 – CHAPTER 6 – THETHE CHEMISTRYCHEMISTRY OFOF LIFELIFE

SECTION 6.1 – Atoms + SECTION 6.1 – Atoms + their Interactionstheir Interactions

p. 141-151p. 141-151

AtomsAtoms: The Building Blocks of : The Building Blocks of Rocks - and You…Rocks - and You…

Both living and nonliving things are Both living and nonliving things are composed of the basic building composed of the basic building blocks called blocks called ATOMSATOMS

ElementsElements DefinitionDefinition

A substance that can’t be broken down A substance that can’t be broken down into simpler chemical substancesinto simpler chemical substances

Examples:Examples: GoldGold TungstenTungsten HeliumHelium

ElementsElements Only about Only about 2525 elements are essential elements are essential

to living thingsto living things Four make up Four make up 96%96% of a human body: of a human body:

CarbonCarbon HydrogenHydrogen OxygenOxygen NitrogenNitrogen

ElementsElements Elements are Elements are

identified by a identified by a symbolsymbol C – CarbonC – Carbon Ca – CalciumCa – Calcium

Trace elementsTrace elements Elements present in Elements present in

small amounts in small amounts in living thingsliving things

Examples:Examples: IronIron CopperCopper ZincZinc IodineIodine

AtomsAtoms: The Building Blocks of : The Building Blocks of ElementsElements

DefinitionDefinition The smallest particle of an element that The smallest particle of an element that

has the characteristics of that elementhas the characteristics of that element Basic building block of all matterBasic building block of all matter

AtomAtom - Structure - Structure NucleusNucleus

Center of the atomCenter of the atom Contains:Contains:

ProtonsProtons Positively charged Positively charged

particles (pparticles (p++)) NeutronsNeutrons

Particles with no Particles with no charge (ncharge (n00))

Nucleus has a Nucleus has a positivepositive charge charge

AtomAtom - Structure - Structure Elements differ in the number of Elements differ in the number of

protonsprotons each has each has Example:Example:

Iron vs. AluminumIron vs. Aluminum

AtomAtom - Structure - Structure ElectronsElectrons

Small, negatively charged particles that Small, negatively charged particles that surround the nucleus (esurround the nucleus (e--))

Held in place by its attraction to pHeld in place by its attraction to p++ in nucleus in nucleus Found in Found in electronelectron cloudsclouds

# electrons is energy levels# electrons is energy levels 11stst – 2 – 2 22ndnd – 8 – 8 33rdrd – 18 – 18

Electron energy levelsElectron energy levels

IsotopesIsotopes DefinitionDefinition

Atoms of the same element that have Atoms of the same element that have different numbers of neutronsdifferent numbers of neutrons

Examples:Examples: C-12C-12 C-13C-13 C-14C-14

IsotopesIsotopes Uses of isotopes:Uses of isotopes:

Some are Some are radioactiveradioactive and therefore can and therefore can be used in be used in radiation treatmentsradiation treatments

Can be used to estimate age of objects Can be used to estimate age of objects ((radioactive datingradioactive dating))

Compounds + BondingCompounds + Bonding CompoundCompound

A substance composed of atoms of two A substance composed of atoms of two or more different elements that is or more different elements that is chemically combinedchemically combined

Example:Example: TABLE SALT - TABLE SALT - NaClNaCl

Most elements in Most elements in nature are found in nature are found in compoundscompounds Atoms combine with Atoms combine with

other atoms to become other atoms to become stablestable

Outermost energy level Outermost energy level is filledis filled

Is this atom stable?Is this atom stable?

Compounds + BondingCompounds + Bonding

Types of BondsTypes of Bonds CovalentCovalent

When two or more atoms share When two or more atoms share electronselectrons

Example:Example:

Hydrogen, HHydrogen, H22

Most compounds in organisms have Most compounds in organisms have covalent bondscovalent bonds

Sugars, fats, proteins, + waterSugars, fats, proteins, + water

Types of BondsTypes of Bonds MoleculeMolecule

A group of atoms held together by a A group of atoms held together by a covalent bondcovalent bond

Example:Example: WATER WATER

Types of BondsTypes of Bonds Ionic bondIonic bond

The attractive force between two ions of The attractive force between two ions of opposite chargeopposite charge

Formed by combining Formed by combining ionsions – a charged – a charged particle made of atomsparticle made of atoms

Opposites attract – “+” like “-”Opposites attract – “+” like “-” Example:Example:

Table SaltTable Salt

How an Ionic bond forms…How an Ionic bond forms…

Chemical ReactionsChemical Reactions Occurs when bonds are Occurs when bonds are formedformed or or

brokenbroken, causing substances to , causing substances to recombine into different substancesrecombine into different substances

Occurs within Occurs within cellscells MetabolismMetabolism

All the chemical reactions that occur All the chemical reactions that occur within an organismwithin an organism

Chemical ReactionsChemical Reactions Chemical reactions are represented Chemical reactions are represented

by writing by writing CHEMICALCHEMICAL EQUATIONSEQUATIONS Example – the formation of waterExample – the formation of water 22 HH22 + + 11OO22 22 HH22OO

ReactantsReactants ProductsProducts CoefficientsCoefficients

Indicates the # of moleculesIndicates the # of molecules SubscriptsSubscripts

Indicates the # of atomsIndicates the # of atoms Equations must be Equations must be BALANCEDBALANCED!!!!!!

Mixtures + SolutionsMixtures + Solutions MixtureMixture

A combination of substances in which A combination of substances in which the individual components retain their the individual components retain their own propertiesown properties

Example:Example: Sugar + WaterSugar + Water Trail MixTrail Mix

SolutionsSolutions DefinitionDefinition

A mixture in which one A mixture in which one or more substances or more substances are distributed evenly are distributed evenly in anotherin another

Parts:Parts: Solute Solute

Substance that gets Substance that gets dissolveddissolved

SolventSolvent Substance doing the Substance doing the

dissolvingdissolving

ConcentrationConcentration DefinitionDefinition

Amount of solute Amount of solute dissolved in fixed dissolved in fixed amount of solventamount of solvent

The more solute The more solute dissolved in the dissolved in the solvent, the greater solvent, the greater the concentration of the concentration of the solutionthe solution

Acids + BasesAcids + Bases Chemical reactions can occur only Chemical reactions can occur only

when conditions are rightwhen conditions are right A reaction may depend upon:A reaction may depend upon:

Available energyAvailable energy TemperatureTemperature Concentration of substanceConcentration of substance pHpH

Acids + BasesAcids + Bases pHpH

A measure of how acidic or basic a A measure of how acidic or basic a solution issolution is

Scale ranges from 0 to 14Scale ranges from 0 to 14

Acids + BasesAcids + Bases AcidAcid

Substance that forms HSubstance that forms H++ ions in water ions in water pH range – below 7pH range – below 7 Typically sour to taste; can be corrosive Typically sour to taste; can be corrosive Examples:Examples:

LemonLemon TomatoTomato Stomach acidStomach acid

Acids + BasesAcids + Bases NeutralNeutral

Substance that has pH value = 7Substance that has pH value = 7 Example:Example:

Pure waterPure water

Acids + BasesAcids + Bases BaseBase

Substance that forms hydroxide ions Substance that forms hydroxide ions (OH(OH--) in water) in water

pH range – above 7pH range – above 7 Typically bitter to taste; feels slipperyTypically bitter to taste; feels slippery Examples:Examples:

EggEgg Drain cleanerDrain cleaner AntacidAntacid