| Term | Definition |
|---|---|
| biomolecule | A large organic molecule such as a protein, nucleic acid, carbohydrate, or lipid that is essential to living organisms. |
| contact area | The surface area between molecules that affects the strength of London dispersion forces. |
| dipole moment | A measure of the separation of positive and negative charge in a polar molecule. |
| dipole-dipole interactions | Intermolecular forces between polar molecules resulting from the attraction between their permanent dipoles. |
| dipole-induced dipole interactions | Attractive forces between a polar molecule and a nonpolar molecule, where the polar molecule induces a temporary dipole in the nonpolar molecule. |
| electron cloud | The region surrounding an atom or molecule where electrons are distributed. |
| electronegative atom | An atom with a strong tendency to attract electrons in a covalent bond, such as nitrogen, oxygen, or fluorine. |
| hydrogen bonding | A strong intermolecular force occurring when hydrogen atoms bonded to highly electronegative atoms (N, O, F) are attracted to the negative end of a dipole in another molecule or region. |
| intermolecular forces | Attractive forces between separate molecules or particles that determine many properties of liquids and solids, including boiling point, melting point, and vapor pressure. |
| ion-dipole interactions | Attractive forces between an ion and a polar molecule, where the charged ion interacts with the partial charges on the polar molecule. |
| London dispersion forces | Intermolecular forces resulting from Coulombic interactions between temporary, fluctuating dipoles in molecules. |
| noncovalent interactions | Weak attractive or repulsive forces between molecules or regions of molecules that do not involve the breaking or formation of covalent bonds. |
| nonpolar molecule | A molecule with no net dipole moment due to symmetrical charge distribution. |
| partial charge | A fractional electric charge on an atom within a molecule due to unequal sharing of electrons in a covalent bond. |
| pi bonding | Covalent bonding formed by the sideways overlap of p orbitals, which enhances polarizability. |
| polar molecule | A molecule with an uneven distribution of charge, resulting in a net dipole moment. |
| polarizability | The ability of a molecule's electron cloud to be distorted, creating a temporary dipole in response to an external electric field. |
| temporary dipole | A brief, fluctuating separation of charge in a molecule caused by uneven electron distribution at any given moment. |
| van der Waals forces | A broad category of weak intermolecular forces including London dispersion forces and dipole-dipole interactions. |
| Term | Definition |
|---|---|
| aqueous solvents | Solvents in which water is the dissolving medium, commonly used in chemistry due to water's polar nature. |
| intermolecular interactions | Forces between molecules, such as hydrogen bonding, dipole-dipole forces, and London dispersion forces, that affect the physical and chemical properties of substances. |
| ionic compound | Compounds formed by the electrostatic attraction between positively charged cations and negatively charged anions. |
| miscible | Capable of being mixed in all proportions without separating into distinct phases. |
| molecular compound | Compounds composed of molecules held together by covalent bonds, typically formed between nonmetals. |
| nonaqueous solvents | Solvents that do not use water as the dissolving medium, such as organic solvents or liquid ammonia. |
| solubility | The maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature, typically expressed in moles per liter (molarity) or grams per 100 mL of solvent. |
| Term | Definition |
|---|---|
| electromagnetic spectrum | The range of all types of electromagnetic radiation, organized by wavelength and frequency, from radio waves to gamma rays. |
| electronic energy levels | Discrete energy states that electrons can occupy in an atom or molecule. |
| electronic transition | The movement of an electron between different energy levels in an atom or molecule, which occurs when a photon is absorbed or emitted. |
| infrared radiation | Electromagnetic radiation with wavelengths between microwave and visible light, associated with molecular vibrational transitions. |
| microwave radiation | Electromagnetic radiation with longer wavelengths and lower frequencies than infrared, associated with molecular rotational transitions. |
| molecular rotational levels | Discrete energy states associated with the rotation of a molecule around its axis. |
| molecular vibrational levels | Discrete energy states associated with the vibration of atoms within a molecule. |
| photon absorption | The process by which matter takes in energy from electromagnetic radiation. |
| photon emission | The process by which matter releases energy in the form of electromagnetic radiation. |
| ultraviolet/visible radiation | Electromagnetic radiation with shorter wavelengths and higher frequencies than infrared, associated with electronic transitions. |
| Term | Definition |
|---|---|
| absorbed photon | A photon taken in by an atom or molecule, increasing the energy of the species by an amount equal to the photon's energy. |
| electromagnetic wave | A wave composed of oscillating electric and magnetic fields that travels at the speed of light and carries energy related to its frequency. |
| electronic transition | The movement of an electron between different energy levels in an atom or molecule, which occurs when a photon is absorbed or emitted. |
| emitted photon | A photon released by an atom or molecule when an electron transitions to a lower energy level, decreasing the energy of the species. |
| frequency | The number of wave cycles that pass a point per unit time, represented by the symbol ν, related to wavelength and the speed of light. |
| photon | A discrete packet of electromagnetic energy with properties related to the frequency and wavelength of light. |
| Planck's constant | The fundamental constant (h) that relates the energy of a photon to its frequency in Planck's equation. |
| Planck's equation | The relationship E = hν that describes how the energy of a photon is proportional to its frequency, where h is Planck's constant. |
| speed of light | The constant velocity at which electromagnetic radiation travels, represented by the symbol c, equal to approximately 3.00 × 10⁸ m/s. |
| wavelength | The distance between successive peaks of an electromagnetic wave, represented by the symbol λ. |
| Term | Definition |
|---|---|
| absorbance | The measure of the amount of light absorbed by a solution, related to concentration and path length when wavelength is held constant. |
| concentration | The amount of solute dissolved in a given volume of solution, typically expressed in molarity or other units of amount per volume. |
| light absorption | The process by which molecules or ions in a solution take in light energy, reducing the intensity of light passing through the solution. |
| maximum absorbance | The wavelength at which a chemical species absorbs the greatest amount of light, also called the optimum wavelength, used to ensure maximum sensitivity in spectrophotometric measurements. |
| molar absorptivity | A constant, denoted as ε, that describes how intensely a specific chemical species absorbs light at a particular wavelength. |
| path length | The distance that light travels through a solution, typically denoted as b in the Beer-Lambert law equation, which is proportional to light absorption. |
| spectrophotometer | An instrument used to measure the absorbance of light by a solution at specific wavelengths. |
| wavelength | The distance between successive peaks of an electromagnetic wave, represented by the symbol λ. |
| Term | Definition |
|---|---|
| boiling point | The temperature at which a liquid vaporizes, directly related to the strength of intermolecular interactions that must be overcome. |
| brittle | The property of a material that causes it to break or shatter easily when subjected to stress, characteristic of ionic solids due to repulsion of like charges. |
| covalent network solids | Solids in which atoms are covalently bonded together in continuous three-dimensional or two-dimensional networks, such as diamond and graphite. |
| ductile | The property of a material that allows it to be drawn or stretched into thin wires without breaking. |
| intermolecular forces | Attractive forces between separate molecules or particles that determine many properties of liquids and solids, including boiling point, melting point, and vapor pressure. |
| interstitial alloy | An alloy in which smaller atoms occupy the spaces between larger atoms in the crystal lattice, making the structure more rigid and decreasing malleability and ductility. |
| ionic solids | Solids composed of cations and anions held together by strong electrostatic forces, characterized by low vapor pressures, high melting and boiling points, and brittleness. |
| macroscopic properties | Observable physical and chemical characteristics of a substance that can be measured at the bulk level, such as melting point, boiling point, and vapor pressure. |
| malleable | The property of a material that allows it to be hammered or pressed into thin sheets without breaking. |
| melting point | The temperature at which a solid transitions to a liquid, which tends to correlate with the strength of intermolecular interactions. |
| metallic solids | Solids composed of metal atoms with delocalized valence electrons that move freely, resulting in good electrical and thermal conductivity, malleability, and ductility. |
| molecular solids | Solids composed of distinct molecules held together by relatively weak intermolecular forces, generally having low melting points. |
| molten state | The liquid state of an ionic solid in which ions are mobile and able to conduct electricity. |
| noncovalent interactions | Weak attractive or repulsive forces between molecules or regions of molecules that do not involve the breaking or formation of covalent bonds. |
| particulate-level structure | The arrangement and organization of atoms, ions, or molecules that make up a substance at the atomic and molecular scale. |
| polymers | Large molecules composed of repeating units of smaller molecules linked together, whose properties depend on noncovalent interactions and molecular shape. |
| valence electrons | Electrons in the outermost shell of an atom that participate in bonding and determine many properties of substances. |
| vapor pressure | The pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. |
| Term | Definition |
|---|---|
| amorphous solid | A solid in which particles do not have a regular or orderly arrangement. |
| collision frequency | The number of collisions between reactant particles per unit time. |
| crystalline solid | A solid in which particles are arranged in a regular, repeating three-dimensional structure. |
| gas | A phase of matter in which particles are in constant motion with minimal intermolecular forces, resulting in no definite volume or shape. |
| hydrogen bonding | A strong intermolecular force occurring when hydrogen atoms bonded to highly electronegative atoms (N, O, F) are attracted to the negative end of a dipole in another molecule or region. |
| interparticle interactions | Forces between particles in a system that affect the energy changes during physical and chemical processes. |
| liquid | A phase of matter in which particles are in close contact and in continual motion and collision with one another. |
| molar volume | The volume occupied by one mole of a substance; typically similar between solid and liquid phases because particles are in close contact. |
| particulate model | A representation of matter showing individual atoms, molecules, or ions and their interactions to describe chemical processes at the molecular level. |
| polarity | The distribution of electric charge in a molecule, determining its ability to interact with polar and nonpolar substances. |
| Term | Definition |
|---|---|
| Dalton's Law of Partial Pressures | The principle that the total pressure of a gas mixture equals the sum of the partial pressures of the individual gas components. |
| ideal gas law | The equation PV = nRT that relates pressure, volume, number of moles, and temperature of an ideal gas. |
| macroscopic properties | Observable physical and chemical characteristics of a substance that can be measured at the bulk level, such as melting point, boiling point, and vapor pressure. |
| mole fraction | The ratio of the number of moles of one component to the total number of moles in a mixture, used to relate partial pressure to total pressure. |
| partial pressure | The pressure exerted by a single gas in a mixture of gases, used in equilibrium expressions for gas-phase reactions. |
| Term | Definition |
|---|---|
| average kinetic energy | The mean kinetic energy of particles in a sample, related to the average velocity by the equation KE = 1/2 mv². |
| Kelvin temperature | Absolute temperature measured on the Kelvin scale, which is directly proportional to the average kinetic energy of particles in a sample. |
| kinetic molecular theory (KMT) | A theory that relates the macroscopic properties of gases to the motion and kinetic energy of particles at the molecular level. |
| macroscopic properties | Observable physical and chemical characteristics of a substance that can be measured at the bulk level, such as melting point, boiling point, and vapor pressure. |
| Maxwell-Boltzmann distribution | A curve that describes how particle energies are distributed in a sample at a given temperature, used to estimate the fraction of collisions with sufficient energy to produce a reaction. |
| particulate model | A representation of matter showing individual atoms, molecules, or ions and their interactions to describe chemical processes at the molecular level. |
| random motion | The continuous, unpredictable movement of particles in all directions with varying speeds. |
| Term | Definition |
|---|---|
| condensation | The process by which a gas converts to a liquid. |
| interparticle attractions | Attractive forces between gas molecules that reduce pressure and cause real gases to deviate from ideal behavior. |
| interparticle forces | Attractive or repulsive forces between gas molecules that cause deviations from ideal gas behavior, particularly at conditions near condensation. |
| non-ideal behaviors | Deviations from the predictions of the ideal gas law that occur when real gases do not follow the assumptions of the ideal gas model. |
| particle volumes | The actual volume occupied by gas molecules themselves, which becomes significant at extremely high pressures and causes deviations from ideal gas law predictions. |
| Term | Definition |
|---|---|
| heterogeneous mixture | A mixture in which macroscopic properties vary depending on the location within the mixture. |
| homogeneous mixture | A mixture with uniform composition and properties throughout the sample. |
| macroscopic properties | Observable physical and chemical characteristics of a substance that can be measured at the bulk level, such as melting point, boiling point, and vapor pressure. |
| molarity | A measure of solution concentration expressed as the number of moles of solute dissolved per liter of solution. |
| solute | The substance being dissolved in a solution, typically present in a smaller amount than the solvent. |
| solution | A homogeneous mixture in which one or more solutes are uniformly dissolved in a solvent. |
| solvent | The substance, typically a liquid, in which a solute dissolves to form a solution. |
| Term | Definition |
|---|---|
| concentration | The amount of solute dissolved in a given volume of solution, typically expressed in molarity or other units of amount per volume. |
| interaction | The forces or bonds between components in a mixture, such as hydrogen bonding, ionic interactions, or dispersion forces. |
| mixture | Materials that contain atoms, molecules, or formula units of two or more types, whose relative proportions can vary. |
| particulate model | A representation of matter showing individual atoms, molecules, or ions and their interactions to describe chemical processes at the molecular level. |
| solution | A homogeneous mixture in which one or more solutes are uniformly dissolved in a solvent. |
| Term | Definition |
|---|---|
| chromatogram | The visual result of a chromatography separation showing the separated components as distinct spots or bands. |
| chromatography | A separation technique that separates chemical species based on differences in their intermolecular interactions with a mobile phase and a stationary phase. |
| column chromatography | A chromatographic separation technique using a column filled with a stationary phase material through which a mobile phase flows. |
| distillation | A separation technique that separates chemical species based on differences in their vapor pressures and boiling points. |
| filtration | A separation technique that uses a physical barrier to separate solid particles from a liquid or gas based on particle size. |
| intermolecular interactions | Forces between molecules, such as hydrogen bonding, dipole-dipole forces, and London dispersion forces, that affect the physical and chemical properties of substances. |
| liquid solution | A homogeneous mixture where a solute is dissolved in a liquid solvent, forming a single phase. |
| mobile phase | In chromatography, the solvent or gas that moves through the stationary phase and carries the components of a mixture. |
| paper chromatography | A chromatographic separation technique using paper as the stationary phase and a liquid solvent as the mobile phase. |
| polarity | The distribution of electric charge in a molecule, determining its ability to interact with polar and nonpolar substances. |
| stationary phase | In chromatography, the solid or liquid material that remains fixed and interacts with the components of a mixture to separate them. |
| thin-layer chromatography | A chromatographic separation technique using a thin layer of absorbent material on a solid support as the stationary phase. |
| vapor pressure | The pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. |