Properties of Water

2-2: Properties of Water Liquid on the Earth’s surface has physical and chemical properties found in no other material covers 75% of Earth has an uneven distribution of electrons and is slightly charged on each end

The BLUE Planet Water is the single most abundant compound in most living things. Liquid at room temperature. Expands when it freezes. Floats in a solid state.

Unique Properties of Water 1. Water is a POLAR molecule. 2. Can attract each other. 3. Not always pure and can be found as part of a mixture. 4. Can react to form ions.

Water is a POLAR Molecule Water carries a slightly negative charge on the O atom and a slightly positive charge on the H atoms. Acts like a magnet. Polar covalent bond in water is due to uneven distribution of electrons between oxygen and hydrogen atoms.

Attraction of Opposite Charges Cohesion is the attraction between molecules of the same substance. Hydrogen bonding. Adhesion is the attraction between molecules of different substances.

Water Often forms Mixtures Mixture - Composed of two or more elements or compounds that are physically mixed together but not chemically combined Sugar and sand Earth’s atmosphere is a mixture of gases

Two Important Water Mixtures 1. solution: a homogeneous mixture in which one substance is dissolved in another solvent: substance that does the dissolving solute: the substance that is dissolved 2. suspension: mixture containing nondissolved particles distributed within a solid, liquid, or gas

Acids and Bases acids: compounds that have higher concentrations of H + ions than pure water. Form H+ ions in a solution Have a pH lower than 7 HCl (Hydrochloric Acid) is a strong acid bases: compounds that have lower concentrations of H+ ions than pure water. Form OH- ions in solution Have a pH higher than 7 Bleach is a strong base Buffers: weak acids or bases that prevent sharp changes in pH levels to help maintain homeostasis.

The pH Scale pH scale: a measurement system that indicates the concentration of hydrogen ions in solution. neutralization reaction: reaction that occurs when H+ ions of a strong acid react with the OH- ions of a strong base form water and a salt.

Relative Concentrations of H+ Ions Concentrations of acids and bases are measured in powers of 10. Used to represent the relative strength of an acid or base compared to another one. A substance with a pH of 4 is 100 times more acidic than a substance with a pH of times is equal to 10 2 How much more acidic is a solution with pH 3 compared with a solution having a pH of 8?

How does a gecko stick to the surface of a wall? Remember what a covalent bond is? Does an e- always remain in one place?

The Answer… Rapid movement of electrons can still create tiny positive or negative charges. Geckos can defy gravity. A gecko’s foot can come in contact with an extremely large surface of the wall at a molecular level. Thousands of hair-like projections Van der Waals Forces are slight attractions between the oppositely charged regions of nearby molecules.

2-3 Chemistry of Carbon Organic Compounds Compounds containing C Forms covalent bonds that are strong and stable 4 single covalent bonds C can form chains of almost unlimited length C – C – C – C – C – C - C Single, double, or triple bonds can form rings

Inorganic Compounds What is an inorganic compound? one exception is CO 2 living things contain many inorganic compounds What are some examples found in us?

Polymerization Building of macromolecules by the joining together of smaller compounds monomers: smaller units which join together to form  polymers: larger compounds which join together to form  macromolecules: giant molecules made of hundreds or thousands of smaller molecules.

Monomers and Polymers

Dehydration and Hydrolysis Opposite reactions that build up or breakdown molecules. Dehydration reaction is the combining of two smaller molecules to form one larger molecule resulting in the loss of water. Hydrolysis reaction is the breaking down of one larger molecule into two smaller molecules by the addition of water.

1. Carbohydrates Carbohydrates are the main source of energy for living things. made of carbon, hydrogen, and oxygen atoms C:H:O 1:2:1 Ratio simplest carbohydrates are monosaccharides glucose galactose (milk) fructose (fruits)

Functions of Carbohydrates 1. Main source of energy 2. Used for structural purposes in plants and some animals Cellulose in plants Strong and flexible Is cellulose a monosaccharide or a polysaccharide? WHY?

polysaccharide: a complex carbohydrate Glycogen (animal starch) stores excess sugar. Released into blood when sugar is low. Which organ is responsible for doing this?

2. Lipids PROPERTIES Not soluble in water Mostly made of C and H atoms Fats, oils, waxes FUNCTIONS 1. store energy 2. form membranes and waterproof coverings 3. chemical messengers (Steroids) Made of 2 or 3 fatty acids combining with a glycerol

Saturated vs. Unsaturated Fats Which of these two types of fats is a healthy fat? WHY?

saturated fat: contains all C – C single bond Meats and dairy products unsaturated fat: contains one C = C double bond Liquid at room temperature. Olive oil polyunsaturated fat: contains more than one C = C bond Cooking oils such as canola, soy, and peanut.

3. Nucleic Acids composed of CHNOP Monomers called Nucleotides have 3 basic parts 5-carbon sugar nitrogenous base Phosphate group

Nucleic Acids FUNCTION Store and transmit hereditary or genetic information. DNA (Deoxyribonucleic acid) deoxyribose sugar RNA (Ribonucleic acid) ribose Sugar

4. Proteins Contain C, N, O, and H 20 different monomers called amino acids peptide bond: a covalent bond that joins two amino acids What process is taking place in the diagram?

Proteins R-group is the side chain section of an amino acid that differs.

Functions of Proteins 1. Control rate of reactions and regulate cell processes. 2. Form bones and muscles 3. Transport substances into/out of cells 4. Fight diseases Four levels of Organization 1. Chain of AA 2. AA in chain twisted and folded 3. Chain itself is twisted and folded 4. Chains have specific arrangements

“Bio-Style” Review

DO NOW ANSWERED A peptide bond is a covalent bond that joins a pair of amino acids together. The Amino Group from the first amino acid and the Carboxyl Group from a second amino acid bond together through a DEHYDRATION Reaction. Water is lost during this reaction and a covalent bond is formed.

2-4: Chemical Reactions and Enzymes Any process in which a chemical change occurs or transforms one set of chemicals into another. Any process in which a chemical change occurs or transforms one set of chemicals into another. Iron + Oxygen  RUST Iron + Oxygen  RUST Occurs slowly Occurs slowly Carbon Dioxide + Water  Carbonic Acid Carbon Dioxide + Water  Carbonic Acid OCCURS QUICKLY Carbonic Acid  Carbon Dioxide + Water Carbonic Acid  Carbon Dioxide + Water

2-4 Chemical Reactions and Enzymes REACTANTS  PRODUCTS C 6 H 12 O O 2  6 CO H 2 O + Energy Flow of energy determines if a reaction will occur Flow of energy determines if a reaction will occur Reactions that release energy occur spontaneously Reactions that release energy occur spontaneously Reactions that require energy will not Reactions that require energy will not (MUST HAVE A SOURCE OF ENERGY) (MUST HAVE A SOURCE OF ENERGY) EXAMPLE of a Spontaneous Reaction?

Energy in Reactions ACTIVATION ENERGY: energy need to start a reaction (start up energy) catalyst: a substance that speeds up the rate of a chemical reaction are not used up work by lowering the “start- up” energy of a reaction

ENZYMES enzymes: proteins that act as biological catalysts. Lower activation energy speed up reactions by binding to reactants known as substrates substrates bind to enzymes at a region known as the active site One specific substrate will bind to one specific active site

ENZYME–SUBSTRATE COMPLEX FIGURE 2-21 of your textbook. Chemical reactions require enough energy to break the existing bonds of the reactants so new bonds will be formed. What will happen to the rate of activity if energy is not available?

Regulation of ENZYME Activity Enzymes can be affected by different factors. These same factors also affect chemical reactions. Enzymes work most effectively at different levels of pH and Temperature Provide an example of these conditions. Dependent upon their specific role in the body.

Regulation of Enzyme Activity Most enzymes work best at 37 degrees C In cells, proteins work as on/off switches. Enzymes regulate chemical pathways, make materials cells need/use, release energy, and transfer information.