The Chemical Basisof Life

All living things need water.

WHY?• Universal solvent• Dissolves necessary nutrients• Used to produce enzymes and hormones Necessary for life processes• Can conduct electricity

Water is the universal solvent.

Remember polarity-uneven charge distribution on a compound

electrons are shared ondifferent energy shells

electrons are shared unequally(someone’s a bully)

Polarity is important to solubility-the abilityOf a solvent to dissolve a solute.

Ionic solutes: ionic solutes are made of ions- charged atoms—one negative, one positive

Water has a positive end and a negative endwhich will exert attractive forces on thesolute

POLARITYUNEVEN DISTRIBUTION OF CHARGESMolecules tend to be asymmetric

__ +

On polar molecules, electrons are controlled by oneOf the atoms.

Polarity – the uneven distribution of charges on a moleculeuneven distribution is a result of:

a. Sharing of electrons between atoms with different energy

1. Asymmetric molecules are polar

Electrons are veryPresent on this sideOf the molecule

That makes this sideOr pole of the moleculeFeel negative

This side or pole of theMolecule has no Electrons present.The charge of the nucleusIs felt making it feelpositive

Hydrogen has one electron on the K shellFluorine has 9 electrons on the K and L shells. Fluorine is a larger atom withMore energy. F controls all of the electrons.

In the water molecule, hydrogen is a smaller atom with less energy than oxygen.When the electrons are share between these two atoms, oxygen controls the electrons because it is an atom with more energy.

Because of this the molecule has two poles – one that feels positive (hydrogen’s end) and the other that feels negative (oxygen’s end).

Well how does all this connect with solutions? The reason why solutes stay in solutionis because of polarity. Polar solutes dissolve most easily in polar solvents – water is polarand so it can dissolve all polar molecules. Nonpolar solvents dissolve nonpolar solutes.

NaCl

NaCl is an ionic compoundthat is made up of + Naions and - Cl ions.NaClWhen an ionic compounddissolves in water it is called DISSOCIATION.

Na +Na +

Na +

Na +

Na + Na +

Na +Na +

Na +

Na +

Na +

Na +Na +

Na +

Na + Na +

Na +

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl - Cl -

Cl -Cl -

Molecules can also be nonpolar – an even distribution of charge on the molecule. a. Sharing of electrons between atoms of equal energy

1. Diatoms

Here this diatom, electrons are on the same energy level. Electrons are on the sameenergy shells and therefore are controlled equally by each atom. Electrons spin equally around each nucleus.

If a non polar molecule is put into water, it will NOT dissolve because of the like Charges that will meet in the water and the solute.

CH4 is a symmetricmolecule that is non polar. It will notdissolve in waterbecause it will be repelledby the positive pole ofthe water molecule.

Solutions are special kinds of mixtures

Let’s review!!

Element – pure substance homogeneous throughout only one kind of matter present

Compound – pure substance homogenous throughout made from 2 or more elements chemical in nature

Mixture – can be homogeneous or heterogeneous made from 2 or more elements, compounds, or both physical in nature

Special solutions

Suspensions• Made of solute/solvent• Heterogeneous • Solute is suspended in the solvent for a

period of time• Solute will eventually settle out of

solution• Oil and vinegar• Chocolate milk• Sand and water• Blood

Colloids• A special kind of suspension where

the solute is held in the solvent for an extended time period.• Homogeneous • The use of an emulsifier is needed

to keep the solute in suspension.• Mayonnaise• Whipped cream

Acid base comparisonacid• Any aqueous solution that

releases Hydrogen ions in solution.• Generally, any compound

that contains Hydrogen• Will react with metals to

release Hydrogen gas.• Has a pH between 1 and 6.9• Tastes sour• Turns blue litmus red• Will react with a base to

produce a salt + water

base

• Any aqueous solution that releases hydroxyl ions (OH) in solution.• Generally, any compound

that contains the OH ion.• Has a pH between 7 and 14• Tastes bitter• Feels slippery• Turns pink litmus blue.• Will react with an acid to

product a salt + water.

Acid: hydrochloric acid – HCl stomach acid sulfuric acid - H2SO4 car battery acid nitric acid HNO3 fertilizers carbonic acid H2CO3 acid found in sodas

Bases: sodium hydroxide – NaOH Drano human blood potassium hydroxide – KOH soaps calcium hydroxide – Ca(OH)2 hair relaxer, remover, Ca supplement in baby food.

Neutralization reaction: Acid + base = salt + water HCl + NaOH NaCl + HOH pH 2 pH 14 pH 7 pH 7

Compounds come in two types:Inorganic-usually ionic

made of a metal and a nonmetal soluble in water high melting points

crystals and minerals generally referred to as salts

Organic- always covalent contain C, H, O H:O 1:2

many compounds that change shape bonds are weaker than ionic but

are very stable.

Reactions that produce organic compounds:1. polymerization production of large organic

compounds that are produced from smaller compounds.Monomer + monomer = polymerProteins and large carbohydrates are formed through polymerization.

2. dehydration synthesis=when H and OHAre removed from two compounds to form aLarger molecule

glucose plus glucose = maltose + water C6H12O6 + C6H12O6 = C12H22O11 + H2ODehydration means: to take water out

3. Hydrolysis reaction: a large molecule isBroken down to form 2 or more smallermolecules by adding water to the rxn.

Starch + water = smaller glucose molecules

All reactions require a specific amount of energy to produceAn activated complex=unstable atoms. The least amount ofEnergy needed to produce this activated complex is theActivation energy.

Exothermic vs endothermic

Catalysts work to supply more energy to a reaction therebyDecreasing the amount of energy needed to produce anActivated complex or specifically reducing the activationEnergy of the reaction. Catalyst make reaction proceed moreQuickly. Enzymes are called biological catalysts and work the sameWay as chemical catalysts within living organisms. Inhibitors work in the opposite way.

How enzymes work:

Terms to remember: active site, substrate, enzyme-substrate complex,denaturation

4 necessary organic compounds for life

1. Carbohydrates: C.H.O1. Monosaccharides - glucose2. Disaccharides - sucrose3. Polysaccharides – celluloseEnergy: immediate – simple long term – starch

stored – as fat

Proteins:C, H, O, N, Samino acids = monomersenzymescell structurepeptide bondscellular repair, muscle formation, genes

Lipids:C, H, Ofats, oils and waxes – cholesterolsaturated and unsaturatedsingle bonds double/triple bondsenergy: immediate and stored

Nucleic acids: C, H, O, NDNA, RNAnucleotides: sugar (ribose), nitrogen base,

phosphate group (-PO4)inheritance, cell function