Chemsitry Final Study Guide

Chapter 6: Chemical Changes

Definitions

  • Physical Change: A change affecting the form of a substance, but not its chemical formula/composition.

  • Chemical Change: A change resulting in a new substance with a different chemical composition; this type of change is irreversible without additional chemical changes.

Balancing Chemical Equations

  • Equations must be balanced with an equal number of each element on both sides. This shows molar ratios of products to reactants.

  • Steps to balance equations:

    1. Balance the most complex molecules or ions first.

    2. Determine the molar mass of reactants and products.

    3. Calculate the molar ratio.

    4. Use mass ratios to determine grams of reactants or products.

Types of Reactions

  • Exothermic Reaction: Releases heat, indicating a loss of energy.

  • Endothermic Reaction: Absorbs heat, indicating a gain of energy.

  • Combustion Reaction: Involves carbon and hydrogen reacting with O2 to produce CO2 and H2O.

Metabolism and Enzymes

  • Metabolism: The totality of catabolic (breaking down) and anabolic (building up) reactions in the body, all catalyzed by enzymes.

  • Enzymes: Biological catalysts that accelerate reactions and lower activation energy; they are not consumed in the reaction.

  • Catabolic Reactions: Exergonic reactions that break down molecules and release energy.

  • Anabolic Reactions: Endergonic reactions that build molecules and consume energy.

  • Transition State: Unstable state where reactants can break bonds and become activated.

  • Activation Energy: The minimum energy required for a reaction to occur.

Chapter 7: Acids and Bases

Key Concepts

  • Ions: Charged atoms resulting from loss or gain of electrons.

  • Self-Ionization of Water: H2O ⇌ H+ + OH-

  • Proton: A hydrogen ion (H+).

  • Hydronium Ion: H3O+, a hydrogen ion bonded to water.

Definitions of Acids and Bases

  • Bases: Proton acceptors, generate hydroxide ions in solution, fully or partially dissociate (e.g., NaOH fully dissociates; weak bases partially dissociate).

  • Acids: Proton donors, increase the concentration of H+ ions, generate hydronium ions in solution; strong acids fully dissociate (e.g., HCl, HNO3), while weak acids partially dissociate.

  • pH Scale: pH < 7 = acid; pH > 7 = base; pH = 7 = neutral.

Chapter 9: Organic Chemistry

Organic Molecules

  • Comprised mainly of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), and sulfur (S).

  • Carbon can form up to four covalent bonds.

Molecular Geometry (VSEPR Model)

  • Linear: 2 Bonds, 180° angle.

  • Trigonal Planar: 3 Bonds, 120° angle.

  • Tetrahedral: 4 Bonds, 109.5° angle.

  • Trigonal Bipyramidal: 5 Bonds, 90° and 120° angles.

  • Octahedral: 6 Bonds, 90° angle.

Types of Compounds

  • Acyclic: Compounds without rings.

  • Cyclic: Compounds with carbon rings.

  • Heterocyclic: Rings containing at least one non-carbon atom.

Molecular Structures

  • Types of formulas include full structural, condensed structural, and line structures.

Functional Groups

  • Alkane: Single bond.

  • Alkene: Double bond.

  • Alkyne: Triple bond.

  • Classifications:

    • Primary: Bonded to one carbon.

    • Secondary: Bonded to two carbons.

    • Tertiary: Bonded to three carbons.

    • Quaternary: Bonded to four carbons.

Chapter 13: Condensation Reactions

  • Condensation Reactions: Build complex molecules from simpler ones, requiring energy; forms covalent bonds.

  • Implicit steps in condensation:

    1. Remove H from one molecule and OH from another.

    2. Example: Amidation from carboxylic acid and amine.

Chapter 14: Proteins

Protein Structure

  • Amino Acids: The monomers of proteins, total of 20 amino acids.

  • Protein: Polymers formed from one or more polypeptide chains.

  • Structural levels:

    • 1° Primary: Sequence of amino acids.

    • 2° Secondary: Local hydrogen bond interactions, e.g., alpha helices and beta sheets.

    • 3° Tertiary: Three-dimensional structure of single polypeptide chain.

    • 4° Quaternary: Interactions between multiple polypeptide chains.

Functional Groups of Amino Acids

  • Amino Group: NH3, hydrophilic.

  • Carboxyl Group: COOH, acts as an acid, hydrophilic.

  • R Group: Variable side chain of amino acids which determines differences in properties.

Protein Interactions

  • Peptide Bonds: Bonds joining amino acids together.

  • Protein Folding: Formation of hydrophobic core; involves charge interactions between amino acids.

  • Denaturation: Disruption of bonds in a protein, rendering it inactive.

Enzyme Interactions

  • Substrate: The chemical acted on by the enzyme.

  • Enzyme Specificity: Specificity for substrate binding; may involve conformational changes.

  • Cofactors: Substances required for enzyme activity.

  • Inhibition Types:

    • Competitive inhibitors block active sites.

    • Allosteric regulation influences enzyme activity from a different site.