The Chemical Basis of 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 on different energy shells electrons are shared unequally (someone’s a bully)

Polarity is important to solubility-the ability Of 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 end which will exert attractive forces on the solute

POLARITY UNEVEN DISTRIBUTION OF CHARGES Molecules tend to be asymmetric __ + On polar molecules, electrons are controlled by one Of the atoms.

Polarity – the uneven distribution of charges on a molecule uneven distribution is a result of: a. Sharing of electrons between atoms with different energy 1. Asymmetric molecules are polar Electrons are very Present on this side Of the molecule That makes this side Or pole of the molecule Feel negative This side or pole of the Molecule has no Electrons present. The charge of the nucleus Is felt making it feel positive Hydrogen has one electron on the K shell Fluorine has 9 electrons on the K and L shells. Fluorine is a larger atom with More 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 solution is because of polarity. Polar solutes dissolve most easily in polar solvents – water is polar and so it can dissolve all polar molecules. Nonpolar solvents dissolve nonpolar solutes. NaCl NaCl is an ionic compound that is made up of + Na ions and - Cl ions. NaCl When an ionic compound dissolves in water it is called DISSOCIATION. Na + 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 same energy 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. CH 4 is a symmetric molecule that is non polar. It will not dissolve in water because it will be repelled by the positive pole of the 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 comparison acid 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 - H 2 SO 4 car battery acid nitric acid HNO 3 fertilizers carbonic acid H 2 CO 3 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 = polymer Proteins and large carbohydrates are formed through polymerization.

2. dehydration synthesis=when H and OH Are removed from two compounds to form a Larger molecule glucose plus glucose = maltose + water C 6 H 12 O 6 + C 6 H 12 O 6 = C 12 H 22 O 11 + H 2 O Dehydration means: to take water out

3.Hydrolysis reaction: a large molecule is Broken down to form 2 or more smaller molecules by adding water to the rxn. Starch + water = smaller glucose molecules

All reactions require a specific amount of energy to produce An activated complex=unstable atoms. The least amount of Energy needed to produce this activated complex is the Activation energy. Exothermic vs endothermic

Catalysts work to supply more energy to a reaction thereby Decreasing the amount of energy needed to produce an Activated complex or specifically reducing the activation Energy of the reaction. Catalyst make reaction proceed more Quickly. Enzymes are called biological catalysts and work the same Way 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.O 1.Monosaccharides - glucose 2.Disaccharides - sucrose 3.Polysaccharides – cellulose Energy: immediate – simple long term – starch stored – as fat

Proteins:C, H, O, N, S amino acids = monomers enzymes cell structure peptide bonds cellular repair, muscle formation, genes

Dehydration synthesis Peptide bond-bond between carbon and nitrogen in a protein

Lipids:C, H, O fats, oils and waxes – cholesterol saturated and unsaturated single bonds double/triple bonds energy: immediate and stored

Lipids are nonpolar covalent compounds = do not dissolve in water. Important for the formation of membranes. Will form liposomes-sphere that surrounds a small amount of aqueous liquid. Sphere is formed from lipids. Liposomes are important in the delivery of prescription medications, cancer treatments, and nutrients. Lipid sphere is made of a two sided molecule: a head: hydrophilic and a tail: hydrophobic

Nucleic acids: C, H, O, N DNA, RNA nucleotides: sugar (ribose), nitrogen base, phosphate group (-PO4) inheritance, cell function