The Chemistry of Life Chapter 2

Atoms matter is anything that fills space atom-the smallest unit of matter nucleus-center of the atom

Atoms ParticleChargeLocationWeight Proton+Nucleus1 Neutron0Nucleus1 Electron-Electron Cloud 0 2-1

Atoms 6 C Carbon Atomic Number = # of protons (or electrons) Symbol Name Average Atomic Mass = protons + neutrons 2-1

element-pure substance that consists of one type of atom

Isotopes Isotopes – atoms of the same element that contain different numbers of neutrons. –Ex: C-12, C-13, and C

Chemical Compounds Compound – a substance formed by the chemical combination of two more elements. –Example: H 2 0, NaCl 2-1

2 Types of Chemical Bonds

Covalent Bonds A covalent bond forms when two atoms share electrons –Forms molecules like water water (H 2 0)

Ionic Bonds When an atom loses or gains electrons, it becomes electrically charged Charged atoms are called ions Ionic bonds are formed between oppositely charged ions

The Water Molecule Polar molecule – has a positive and negative end because electrons aren’t shared evenly. Allows it to form hydrogen bonds

Solutions Solution – mixture in which all components are evenly distributed. –Solvent – does the dissolving (water) –Solute – gets dissolved (Kool-Aid) 2-2

H 2 O-->H+ & OH- H + = Hydrogen ion in excess= acid OH - = Hydroxide ion in excess= base

Acids, Bases, and pH pH scale– measurement system used to indicate the concentration of hydrogen ions (H + ) in solution; ranges from 0 to 14

Acids, Bases, and pH Acids – form H + ions in solution, pH less than 7. (ex: stomach acid) Bases – form OH - ions in solution, pH greater than 7. (ex: oven cleaner) Buffers – chemicals that prevent sudden changes in pH. 2-2

Carbon! Organic compounds – contain carbon and are associated with living things.

Organic Polymers Polymers – macromolecules made of repeating units called monomers. Four types: carbohydrates, lipids, nucleic acids, proteins. Polymer Monomers 2-3

Carbohydrates Carbohydrates – compounds made of carbon, hydrogen, and oxygen in a ratio usually 1 : 2 : 1. –Energy source!!! –Ex: sugars, starches, glycogen, cellulose –Monosaccharides (monomer) (glucose) –Polysaccharides (polymer) (starch) 2-3

Carbohydrates

Lipids Lipids – made of mostly carbon and hydrogen atoms. –Fats, oils, waxes –Three fatty acids and a glycerol –Store energy, make membranes, waterproof 2-3

Lipids

Nucleic acids Nucleic acids – contain hydrogen, oxygen, carbon, nitrogen, and phosphorus. –Carry genetic information –Monomers = Nucleotides –Ex: DNA and RNA 2-3

Proteins Proteins – contain carbon, hydrogen, oxygen, and nitrogen. –Form bones/muscles, transport substances, fight disease, control reactions, regulate cell processes. 2-3

–Monomers = amino acids Proteins –Peptide bond – bond between amino acids.

Chemical Reactions chemical reaction: a process that changes one set of chemicals into another set of chemicals CO 2 + H 2 O → H 2 CO 3 Reactants Products

CO2 + H2O → H2CO3 Reactants Products

Enzymes Enzymes – proteins that act as catalysts (speed up reactions). –Can be affected by temperature & pH –Don’t get changed in the reaction. 2-4

Enzymes See the animation!

1. An organic catalyst is indicated by letter 2. An enzyme-substrate complex is indicated by letter. Substrate goes into the active site! B C A D