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Introductory Chemistry 2 Unit 2 Chapter 2 Chemical Elements • • • • 2 Fundamental unit in chemistry Cannot be broken down by chemical means 112 elements total Use 1-2 letter symbols for each • • • 26 normally present in your body 4 major ones & 8 others significant (see table 2.1) Unit 2 e.g. C= carbon, Na = sodium, Cl = chorine. Atoms • • • • 2 Lowest unit of an element Nucleus-protons (+), neutrons (0) Surrounded by Electrons (-) Total charge is neutral- • • Proton number=atomic numberdefines element Unit 2 Protons # = electron # • • • • Atoms interact in characteristic ways Describing this is chemistry When two or more atoms are held together with chemical bonds the result is a molecule. Described by the molecular formula 2 Unit 2 Ions, Molecules & Compounds Molecular Formula • 2 Example: O2 = oxygen the gas molecule has 2 atoms of oxygen bound together • H2O = water • • Subscript = # of atoms of element Connected letters & numbers = molecule Unit 2 Molecule has 2 atoms of H (hydrogen) and 1 atom of O (oxygen) Figure 2.3 • • • • attraction between atoms to form attachments = molecules Electrons grouped into shells preferred number in outer shell leads to chemical activity Can be covalent, ionic, polar covalent and Hydrogen bonds 2 Unit 2 Bonding Ionic Bonds • 2 Can donate or accept electrons from another atom -> • • Opposite charges attract => bonding Ionic bonding Unit 2 Ions = atoms with a charge Figure 2.4 Figure 2.4 Covalent Bonds • 2 Can share electrons in outer shell > covalent bonds e.g. water, many organic compounds unequal sharing -> polar bond some partial charges on the molecule Unit 2 • Figure 2.5a Figure 2.5b Figure 2.5c Figure 2.5d Figure 2.5e Chemical Reactions- Synthesis Putting atoms together A + B => AB Eg. 2H2 + O2 => 2 H2O Synthesis in the body = Anabolism Unit 2 • • • • 2 Chemical ReactionsDecomposition Splitting Molecules apart AB => A + B Eg. CH4 => C + 2H2 Decomposition in the body = Catabolism Unit 2 • • • • 2 Other Reactions 2 • Exchange reactions • both decomposition & synthesis E. g. AB + CD => AD + BC E. g. AB <=> A + B Unit 2 • Reversible reactions • Go both directions • • • • • • Good solvent for some molecules Dissolve = Hydrophilic molecules Don’t dissolve = Hydrophobic molecules Participates in chemical reactions Absorbs & releases heat slowly Needs large amount of heat to evaporate 2 Unit 2 Nature of Water • • • Acid dissolves => H+ (1 or more) Base dissolves => OH- ( 1 or more) Acid plus base react => salt • E.g. HCL + KOH => KCL + H2O acid base salt 2 Unit 2 Acid, Base & Salts pH Concept • • • • The concentration of H+ or OHexpressed on the pH scale 0-14 At pH = 7.0: H+conc. = OH- conc. Less than 7.0 = more H+ (acid) The smaller the number, the more H+ More than 7.0 = more OH- (alkaline) The larger the number, the more OH- Unit 2 • 2 Organic Compounds Carbohydrates Lipids Proteins Nucleic acids Unit 2 • • • • 2 Carbohydrates • Simple sugars = Monosaccharide Major one in body = glucose Disaccharides= 2- simple sugars bonded Formed by dehydration synthesis E.g. glucose + fructose => sucrose glucose + galactose => lactose Glucose + glucose => maltose Unit 2 • • • 2 Figure 2.8 Polysacchharides • 2 Many sugars bonded in chains Can have branching structures not usually soluble in water • Glycogen- animal carbohydrate Polyglucose Starch- plant carbohydrate Polyglucose • Cellulose- plant polymer Polyglucose but indigestible = fiber Unit 2 • Figure 2.9 • • • • • • • Insoluble in water = hydrophobic Triglycerides Phospholipids Cholesterol Steroids Fatty acids Fat soluble vitamins 2 Unit 2 Lipids Figure 2.10 Figure 2.11 Figure 2.12 Cholesterol Ring structures Used to make steroid hormones Help make membranes stiff Made in liver Unit 2 • • • • 2 Proteins Structural elements in cells Chemical catalysts Hormones Antibodies Polymers of amino acids Unit 2 • • • • • 2 Amino Acid Amino group Carboxyl group Side chain ~20 different side chains A large variety of structures Unit 2 • • • • • 2 Figure 2.13 Terminology • • • Amino acids joined by peptide bond 2 = dipeptide, 3= tripeptide Many =polypeptide Functional polypeptide = protein Includes structure up to quaternary. Thus a protein may have 1 or more polypeptide chains Unit 2 • 2 Enzymes • • • Proteins serving as chemical catalysts Highly specific Efficient May be controlled Unit 2 • 2 Figure 2.14 Nucleic Acids • Polymer of nucleotides => Phosphate Sugar –pentose (ribose, deoxyribose) Base- 5 of them (4 per nucleic acid) Adenine (A), guanine (G), thymine (T), cytidine (C), uracil (U) Unit 2 • • • 2 • • • • • Deoxyribose & A,T,G,C Bases pair: A-T & G-C Two polymers hydrogen bonded together forms a double helix Stores genetic information on protein sequences. 2 Unit 2 DNA Figure 2.15 RNA Ribose & A,U,G,C Single chain Functions in protein synthesis Required to translate DNA to protein Unit 2 • • • • 2 ATP • Specialized for energy transport in the cell Carries energy in the chemical bond between phosphate groups. Unit 2 • 2 Figure 2.16