Introduction to Chemical Bonding and Solutions
Chemical Bonding
Definitions
Chemical Bond: Mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together.
Ionic Bonding: Chemical bonding that results from the electrical attraction between cations and anions.
Covalent Bonding: Results from the sharing of electron pairs between two atoms.
Electronegativity: A measure of an atom’s ability to attract electrons.
Nonpolar Covalent Bond: A covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge.
Polar Covalent Bond: Covalent bond in which the bonded atoms have an unequal attraction for the shared electrons.
Polar: Uneven distribution of charge.
Molecule: A neutral group of atoms that are held together by covalent bonds.
Molecular Compound: Chemical compound whose simplest units are molecules.
Chemical Formula: Indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts.
Molecular Formula: Indicates the types and numbers of atoms combined in a single molecule of a molecular compound.
Diatomic Molecule: A molecule containing only two atoms.
Bond Energy: Energy required to break a covalent bond and form neutral isolated atoms.
Resonance: The bonding in molecules or ions that cannot be correctly represented by a single Lewis structure.
Ionic Compound: Positive and negative ions (cations and anions) that are combined so that the numbers of positive and negative charges are equal.
Formula Unit: Simplest collection of atoms from which an ionic compound formula can be established.
Lattice Energy: Energy released when one mole of an ionic crystalline compound is formed from gaseous ions.
Polyatomic Ions: A charged group of covalently bonded atoms.
Metallic Bonding: Chemical bonding resulting from the attraction between metal atoms and the surrounding sea of electrons.
Malleability: The ability of a substance to be hammered or beaten into thin sheets.
Ductility: The ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire.
VSEPR Theory
VSEPR Theory: Valence-Shell Electron Pair Repulsion Theory
VSEPR Theory: Repulsion between the sets of valence-level electrons surrounding an atom causes the sets to be oriented as far apart as possible.
Dipole-Dipole Forces: Forces of attraction between polar molecules.
Dipole: Created by equal but opposite charges that are separated by a short distance.
London Dispersion Forces: The intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles; forces act between all atoms and molecules; forces are not present in intramolecular forces; increases with atomic mass or molar mass.
Hybridization: The mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies.
Hybrid Orbitals: Orbitals of equal energy produced by the combination of two or more orbitals on the same atom.
Ions and Compounds
Monatomic Ions: Ions formed from a single atom.
Binary Compounds: Compounds composed of two elements.
Oxyanions: Polyatomic ions that contain oxygen.
Binary Acids: Acids that consist of two elements, usually hydrogen and one of the halogens—fluorine, chlorine, bromine, iodine.
Oxyacids: Acids that contain hydrogen, oxygen, and a third element (usually a nonmetal).
Salt: Ionic compound composed of a cation and the anion from an acid.
Formula Mass: Sum of the average atomic masses of all atoms represented in its formula.
Empirical Formula: A chemical formula that shows the composition of a compound in terms of the relative numbers and kinds of atoms in the simplest ratio.
Hydrocarbons: Molecular compounds composed solely of carbon and hydrogen.
Stock System: Used to distinguish the ions formed when elements form two or more cations with different charges; uses a Roman numeral to indicate an ion’s charge.
Molar Mass: The mass in grams of one mole of a substance; a compound’s molar mass is numerically equal to its formula mass.
Chemical Reactions
Precipitate: A solid that forms from a solution during a chemical reaction.
Reversible Reaction: A chemical reaction in which the products re-form the original reactants.
Synthesis Reaction: A reaction in which two or more substances combine to form a new compound.
Decomposition Reaction: A reaction in which a single compound breaks down to form two or more simpler substances.
Electrolysis: The decomposition of a substance by an electric current.
Single-Displacement Reaction: A reaction in which atoms of one element take the place of atoms of another element in a compound.
Double-Displacement Reaction: When the positive ion of one compound replaces the positive ion of another to form two new compounds.
Combustion Reaction: A chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light.
Activity Series: A list of elements organized according to the ease with which the elements undergo certain chemical reactions.
Composition Stoichiometry: Deals with the mass relationships of elements in compounds.
Reaction Stoichiometry: Calculations involving the mass relationships between reactants and products in a chemical reaction.
Mole Ratio: A conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction.
Limiting Reactant: The substance that controls the quantity of product that can form in a chemical reaction.
Excess Reactant: The substance that is not used up completely in a reaction.
Theoretical Yield: The maximum amount of product that can be produced from a given amount of reactant.
Actual Yield: The measured amount of a product obtained from a reaction.
Percentage Yield: The ratio of the actual yield to the theoretical yield, multiplied by 100.
Gases
Properties and Behavior
Diffusion: Spontaneous mixing of the particles of two substances caused by their random motion.
Effusion: A process by which gas particles pass through tiny openings.
Elastic Collision: Collisions between gas particles, other particles, and container walls—with no net loss of kinetic energy.
Fluids: Liquids or gases that flow.
Ideal Gas: An imaginary gas that perfectly fits all assumptions of the Kinetic Molecular Theory.
Real Gas: A gas that does not behave completely according to the assumptions of the Kinetic Molecular Theory.
Kinetic Molecular Theory: Based on the idea that particles of matter are always in motion.
Pressure and Units
Atmospheric Pressure (Atm): Defined as equivalent to 760 mm Hg.
Barometer: A device used to measure atmospheric pressure.
Pascal: The pressure exerted by a force of one newton acting on an area of one square meter and is symbolized by Pa.
Partial Pressure: The pressure of each gas in a mixture.
Dalton’s Law of Partial Pressures: States that the total pressure of a gas mixture is the sum of the partial pressures of the component gases.
Gas Laws
Boyle’s Law: States that the volume of a fixed mass of gas varies inversely with the pressure at constant temperature.
Charles’ Law: States that the volume of a fixed mass of gas at a constant pressure varies directly with the Kelvin temperature.
Gay-Lussac’s Law: The pressure of a fixed mass of gas at a constant volume varies directly with the Kelvin temperature.
Combined Gas Law: Expresses the relationship between pressure, volume, and temperature of a fixed amount of gas.
Gay-Lussac’s Law of Combining Volumes of Gases: States that at constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers.
Avogadro’s Law: States that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.
Ideal Gas Law: The mathematical relationship among pressure, volume, temperature, and the number of moles of a gas.
Graham’s Law of Effusion: States that the rates of effusion of gases at the same temperature and pressure are inversely proportional to the square roots of their molar masses.
Solutions
Types and Properties
Solution: A homogeneous mixture of two or more substances in a single phase.
Homogeneous: Same throughout.
Heterogeneous: Different throughout.
Soluble: Able to be dissolved.
Insoluble: Not able to be dissolved.
Solvent: The component of the mixture that does the dissolving.
Solute: The substance that is dissolved.
Suspensions: Heterogeneous mixture in which the particles will settle upon standing, can be separated on filtration, and will show the Tyndall effect (e.g., orange juice with pulp).
Colloid: Heterogeneous mixture with particles smaller than a suspension and larger than a solution. Do not separate upon standing, do not separate by filtration, but can show the Tyndall effect.
Electrolyte: Substance that dissolves in water to produce ions, therefore the solution can conduct electricity.
Nonelectrolytes: Substances that dissolve in water but do not break into ions and cannot conduct electricity.
Concentration and Solubility
Molarity: Moles of solute/liters of solution; M.
Factors Affecting the Rate of Dissolution: Increasing the surface area of the solute, agitation, heating.
Solution Equilibrium: The physical state in which the opposing processes of dissolution and crystallization of a solute occur at equal rates.
Saturated: Contains the maximum amount of dissolved solute.
Unsaturated: Contains less than the maximum amount of solute.
Supersaturated: Contains more solute than a saturated solution under the same conditions.
Solubility Values: States the amount of a specific substance required to form a saturated solution with a specific amount of solvent at a specified temperature.
Immiscible: When two liquids will not dissolve in each other (e.g., water and oil).
Miscible: Liquids that dissolve freely in one another in any proportion (e.g., ethanol and water).
William Henry’s Law: The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid.
Effervescence: The rapid escape of gas in a liquid in which it is dissolved.
Solvated: A solute particle that is surrounded by solvent molecules.
Enthalpy of Solution: The amount of heat energy absorbed or released when a specific amount of a solute dissolves in a solvent.
Concentrated: Contains a large amount of solute.