Chemistry 1010 Final Clemson University

Molecule

Unit of matter that results when two or more atoms are joined by covalent bonds

Ionic Bond

A bond resulting from the electrostatic attraction of a cation for an anion.

Nonpolar Covalent Bond

A bond characterized by an even distribution of charge; electrons in the bonds are shared equally by the two atoms

Polar Covalent Bond

A bond resulting from unequal sharing of bonding pairs of electrons between atoms

Polyatomic Ions

Charged group of one or more atoms joined together by covalent bonds

Electrostatic Potential

The energy a charged particle has due to its position relative to another charged particle; directly proportional to the product of the charges of the particles; inversely proportional to the distance between the particles

Lattice Energy

The energy released when 1 mole of an ionic compound forms from its free ions in the gas phase

Bond Energy

The energy needed to break 1 mole of a particular covalent bond in a molecule or polyatomic ion in the gas phase.

Octet Rule

Atoms of main group elements make bonds by gaining, losing, or sharing electrons to achieve a valence shell containing 8 electrons, or four electron pairs

Bond Length

Distance between two bonded atoms at their minimum potential energy, that is, the average distance between two bonded atoms

Bonding Pair

Pair of electrons shared between two atoms

Lone Pair

Pair of electrons that is not shared between two atoms

Electronegativity

A relative measure of the ability of an atom in a chemical compound to attract electrons

Resonance

Characteristic of electron distributions when two or more equivalent Lewis structures can be drawn for one compound

Resonance Structure

One of two or more Lewis structures with the same arrangement of atoms but different arrangements of bonding pairs of electrons

Resonance Stabilization

The stability of a molecular structure due to delocalization of its electrons

Formal Charge

Value calculated for an atom in a molecule or polyatomic ion by determining the difference between the number of valence electrons in the free atom and the sum of lone-pair electrons plus half of the electrons in the atom's bonding pairs

Bond Order

The number of bonds between atoms: 1 for a single bond, 2 for a double bond, and 3 for a triple bond

Bonds are Broken

Energy is released

Bonds are Formed

Energy is absorbed

Bond Angle

The angle (in degrees) defined by lines joining the centers of two atoms to a third atom to which they are chemically bonded

Electronic Geometry

The 3D arrangements of bonding pairs and lone pairs of electrons around a central atom

Molecular Geometry

The 3D arrangement of atoms in a molecule

Bond Dipole

Separation of electrical charge created when atoms with different electronegativities form a covalent bond

Hybridization

In valence bond theory, the mixing of atomic orbitals to generate new sets of orbitals that then are available to form covalent bonds with other atoms

Hybrid Atomic Orbital

In valence bond theory, one of a set of equivalent orbitals about an atom created when specific atomic orbitals are mixed

Molecular Orbital

A region of characteristic shape and energy where electrons in a molecule are located

Bonding Orbital

Term in Molecular Orbital Theory describing regions of increased electron density between nuclear centers that serve to hold atoms together in molecules

Antibonding Orbital

Term in Molecular Orbital Theory describing regions of electron density in a molecule that destabilize the molecule because they do not increase the electron density between nuclear centers

Polar Bonds

Bond between 2 atoms that have a large difference in electronegativity

Polar Molecule

A molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons

Valence Bond Theory

Provides a readily visualized orbital picture of how electron pairs are shared in a covalent bond

Atomic Orbital

A wave function whose square gives the probability of finding an electron within a given region of space in an atom

Molecular Orbital

A wave function whose square gives the probability of finding an electron within a given region of space in a molecule

Intramolecular Forces

Any force that holds together the atoms making up a molecule or compound

Intermolecular Forces

Forces of attraction or repulsion between neighboring particles

Dipole Moment

Quantitative expression of the polarity of a molecule

Temporary Dipole

Intermolecular force between nonpolar molecules caused by the presence of temporary dipoles within the molecules.

Permanent Dipole

Permanent separation of electrical charge in a molecule due to unequal distributions of bonding and/or lone pairs of electrons

Van der Waals Force

Any interaction between neutral atoms and molecules including hydrogen bonds, other dipole-dipole interactions, and London dispersion forces. (Does not apply to interactions involving ions)

London Dispersion Force

An intermolecular force between molecules caused by the presence of temporary dipoles in the molecules

Ion-Dipole Interaction

Attractive force between an ion and a molecule that has a permanent dipole

Dipole-Dipole Interaction

Attraction between regions of polar molecules that have partial charges of the opposite sign

Hydrogen Bond

Strongest dipole-dipole interaction, which occurs between a hydrogen atom bonded to a N,O,F atom and another N,O,F atom.

Polarizability

Relative ease with which the electron cloud in a molecule, ion, or atom can be distorted, including a temporary dipole

Sphere of Hydration

The cluster of water molecules surrounding an ion in an aqueous solution

Alcohol

An organic compound whose molecular structure includes a hydroxyl group bonded to a carbon atom that is not bonded to any other functional groups

Solvent

The component of a solution that is present in the greatest amount

Solute

Any component of a solution other than the solvent

Solubility

The maximum amount of solute that can dissolve in a given amount of solvent at a given temperature and pressure

Miscible

Liquids that dissolve freely in one another in any proportion

Hydrophobic

Describes a substance that does not dissolve in water; water-fearing

Hydrophilic

Describes a substance that dissolves in water; water-loving

Normal Boiling Point

The temperature at which a liquid boils at 1 atm of pressure

Stoichiometry

Mole ratios among the reactants and products in a chemical reaction

Chemical Equation

Description of the identities and proportions of reactants and products

Reactants

Substances consumed during a chemical reaction

Products

Substances formed during a chemical reaction

Molecular Mass

Mass in amu of one molecule of a molecular compound

Formula Mass

Mass in amu of one formula unit of an ionic compound

Law of Conservation of Mass

Principle that the sum of the masses of the reactants in a chemical reaction is equal to the sum of the masses of the products

Percent Composition

Composition of a compound expressed in terms of the percentage by mass of each element in the compound

Empirical Formula

Formula showing the smallest whole number ratio of elements in a compound

Limiting Reactant

Reactant that is consumed completely in a chemical reaction. The amount of product formed depends on the amount of this substance

Theoretical Yield

Maximum amount of product possible in a chemical reaction for the given quantities of reactants

Percent Yield

Ratio, expressed as a percentage, of the actual yield of a chemical reaction to the theoretical yield of the reaction

Molarity

M; the number of moles of solute per liter of solution

Standard Solution

A solution of known concentration that is used in chemical analysis

Dilution

The process of adding solvent to lower the concentration of solute in a solution

Electrolyte

A material that dissolves in water to give a solution that conducts an electric current

Strong Electrolyte

An ionic substance that dissociates completely when it dissolves in water

Weak Electrolyte

A substance that only partly dissociates into ions when it dissolves in water

Nonelectrolyte

A molecular substance that does not dissociate into ions when dissolved in water

Weak Acid

Acid that only partially dissociates in aqueous solutions

Strong Acid

Acid that ionizes completely in aqueous solution

Strong Base

Base that completely dissociates into ions in aqueous solution

Weak Base

Base that does not dissociate completely into ions in solution.

Neutralization Reaction

A reaction that takes place when an acid reacts with a base and produces a solution of a salt in water

Molecular Equation

Balanced equation that describes a reaction in solution in which the reactants are written as undissociated molecules

Spectator Ions

Ion that is unchanged by a chemical reaction

Net Ionic Equation

A balanced equation that describes the actual reaction taking place in solution; it is obtained by eliminating the spectator ions from the total ionic equation

Precipitate

Solid product formed from a reaction in a solution

Titration

An analytical method for determining the concentration of a solute in a sample by reacting the solute with a solution of known concentration

Oxidation-Reduction Reaction

A reaction that results in a change in oxidation states of atoms in the reactants. These two always occur as a set.

Chemical Energy

Potential energy stored in chemical bonds

Kinetic Energy

Energy of motion

Potential Energy

Energy that is stored, either in an object because of its position or in a molecule because of its chemical composition

Internal Energy

The sum of all the kinetic and potential energies of all fo the components of a system

Thermochemistry

Study of the changes in energy that accompany chemical reactions

First Law of Thermodynamics

Principle that the energies gained or lost by a system must equal the energy lost or gained by the surroundings.

System

Part of the universe that is the focus of a thermochemical study

Surroundings

Everything in a thermochemical study that is not part of the system

Thermal Energy

The portion of the total internal energy of a system that is proportional to its absolute temperature

Exothermic Process

One in which energy (usually in the form of heat) flows from a system into its surroundings

Endothermic Process

One in which energy (usually in the form of heat) flows from the surroundings into the system

Work

(w); the distances moved times the force that opposes the motion

Pressure-Volume Work

The work associated with the expansion or compression of a gas

Enthalpy

The sum of the internal energy and the pressure volume product of a system

Enthalpy Change (∆H)

The energy absorbed by the reactants or the energy given off by the products for a reaction carried out at a constant pressure.

Heat Capacity

Energy required to raise the temperature of an object by 1 degree Celsius at constant pressure.