2. Chemical Reactions

Key Elements:

  • Iridium (Ir): Transition metal, used in high-temperature applications and as a hardening agent for platinum.

  • Osmium (Os): Densest naturally occurring element, used in fountain pen nibs and electrical contacts.

Symbols:

  • H3O (Hydronium): Ion representing an acid in aqueous solutions.

  • OH2 (Hydroxide): Ion representing a base and important in pH balance.

Periodic Table of Elements

  • Categories of Elements:

    • Representative Elements (Groups 1-2, 13-18): Includes metals, nonmetals, and metalloids.

      • Alkali Metals: Soft, reactive with water (e.g., Sodium (Na)).

      • Alkaline Earth Metals: Reactive metals (e.g., Calcium (Ca)).

      • Transition Metals: Known for variable oxidation states and complex ion formation.

      • Halogens: Highly reactive nonmetals (e.g., Chlorine (Cl)).

      • Noble Gases: Inert gases with complete electron shells (e.g., Neon (Ne)).

  • Table Structure:

    • Periods: Horizontal rows (1-7) indicating energy levels of electrons.

    • Groups: Vertical columns (1A-8A) indicate elements with similar properties due to similar valence shell configurations.

  • Notable elements:

    • Hydrogen (H): Lightest element, important in acids and bases.

    • Lithium (Li): Used in batteries and mood-stabilizing drugs.

    • Sodium (Na): Essential for life, involved in nerve transmission.

    • Potassium (K): Important for cellular function and heart health.

    • Transition metals such as Iron (Fe) and Copper (Cu) are vital for biological and industrial processes.

Ionic Compounds

  • Definition of Ionic Compound:

    • Formed when electrons are transferred from metals to nonmetals, resulting in the creation of positive ions (cations) and negative ions (anions).

  • Ionic Bonds:

    • Formation occurs through electrical attraction between oppositely charged ions.

    • Examples: Sodium chloride (NaCl), Sodium bicarbonate (NaHCO3), Calcium carbonate (CaCO3).

  • Dissociation in Water:

    • Ionic compounds dissociate into their respective ions when dissolved in solution, leading to conductivity in aqueous solutions.

Chemical Formulas of Ionic Compounds

  • Structure:

    • Employs symbols and subscripts in the lowest whole-number ratio to represent the ionic compound.

    • Ensures that the sum of ionic charges equals zero (positive ions = negative ions).

    • Example: Sodium chloride (NaCl), Magnesium chloride (MgCl2).

Variable Charges in Ionic Compounds

  • Certain metals can exhibit variable charges, necessitating the use of Roman numerals in naming.

    • Iron (Fe) can exist as Fe2+ or Fe3+.

    • Copper (Cu) can exist as Cu2+ or Cu3+.

Naming Ionic Compounds

  • Conventions:

    • Follow traditional naming conventions that are based on the cation and anion. Polyatomic ions often have specific names (e.g., sulfate, nitrate).

Polyatomic Ions

  • Definition:

    • Groups of covalently bonded atoms that exhibit an overall ionic charge.

    • Examples:

    • Calcium sulfate (CaSO4) = Ca2+ + SO4 2-

    • Ammonium nitrate (NH4NO3) = NH4+ + NO3-

Molecular Compounds

  • Definition:

    • Composed of two or more nonmetals sharing valence electrons through covalent bonds, resulting in the formation of discrete molecules.

  • Properties:

    • Do not typically dissociate in water, differing from ionic compounds.

    • Examples:

    • Water (H2O), Carbon dioxide (CO2), Sucrose (C12H22O11).

Naming Molecular Compounds

  • Conventions:

    • Naming based on the number of atoms present and the types of nonmetals involved, using prefixes such as mono-, di-, tri-.

Chemical Reactions

  • Chemical Change:

    • Conversion of substances into new entities called products.

  • Types of Reactions:

    • Combination Reactions:

      • Two or more reactants combine to form a single product.

      • Example: A + B → AB.

    • Decomposition Reactions:

      • A single reactant breaks down into multiple products.

      • Example: AB → A + B.

    • Replacement Reactions:

      • Elements in compounds are replaced by other elements.

      • Single Replacement: A + BC → AB + C.

      • Double Replacement: AB + CD → AD + CB.

    • Combustion Reactions:

      • Hydrocarbons react with oxygen, producing carbon dioxide and water.

    • Oxidation-Reduction Reactions:

      • Involves transfer of electrons, important in energy production and metabolism.

      • Oxidation: loss of electrons.

      • Reduction: gain of electrons.

  • *** OIL RIG mnemonic helps remember the processes: Oxidation Is Loss, Reduction Is Gain.

    • Endergonic Reactions:

      • Absorb more energy than they release; examples include photosynthesis.

    • Exergonic Reactions:

      • Release more energy than they absorb; examples include combustion.

Resources

  • Timberlake, K.C., & Timberlake, W. (2020). Basic Chemistry (6th Edition). New York, NY: Pearson Publishing.

  • Colville, T. & Bassert, J.M. (2024). Clinical Anatomy and Physiology for Veterinary Technicians (4th Edition). St. Louis, MO: Elsevier.

Questions?

  • Open for student inquiries regarding content.