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| chemical change | a process in which one or more reactants are changed into one or more different products. A chemical change occurs whenever compounds are formed or decomposed. During a chemical change, there is a rearrangement of atoms that makes or breaks chemical bonds |
| chemical property | a characteristic of a substance that is measurable or observable during a chemical reaction; includes pH, heat of combustion, reactivity, etc. |
| extensive properties | a property that depends on the size of an object or system |
| indicator | a substance added in small amounts to a solution in order to provide a visual reference for the pH of the solution |
| intensive properties | features of substances that do not vary with quantity |
| phase of matter | the physical forms in which matter exists, as determined by the average kinetic energy of the atoms involved; the most common phases of matter are solid, liquid, gas and plasma; also called state of matter; |
| physical change | a change in only the appearance of matter, usually from one phase of matter to another, that does not affect the chemical composition of the substance. Matter can change from liquid to solid (freezing or solidification); from liquid to gas (evaporation); |
| a change in only the appearance of matter, usually from one phase of matter to another, that does not affect the chemical composition of the substance. Matter can change from liquid to solid (freezing or solidification); from liquid to gas (evaporation); | a characteristic that can be observed (intensive), such as texture, color, odor, melting point, boiling point, density, or measured (extensive) such as mass, length, volume, that is used to describe matter and can be observed or measured without changing its composition |
| precipitate | solid particles that have been separated from a solution |
| sublimation | matter phase change from solid directly to gas |
| alloy | a mixture of a metal and another element, either metal or nonmetal |
| atom | the smallest unit of an element that has all the chemical properties of that element |
| atomic number | the number of protons in the nucleus of an atom |
| chemical property | a characteristic of a substance that is measurable or observable during a chemical reaction; includes pH, heat of combustion, reactivity, etc. |
| colloid | a type of heterogeneous mixture in which fine particles are suspended in a liquid, solid, or gas medium |
| compound | a pure substance that is formed when two or more different elements combine; can usually be separated into component elements by chemical reaction |
| element | a pure substance that cannot be broken down into simpler substances by chemical reactions and that is made up of only one type of atom |
| emulsion | a mixture of two or more liquids that are not soluble in each other |
| gas | a state of matter without any defined volume or shape in which atoms or molecules move about freely |
| heat energy | a form of energy that transfers between particles in a substance or system through kinetic energy transfer |
| heterogeneous | made up of two or more distinct components; usually refers to a mixture in which individual substances are distinct |
| homogeneous | made up of one uniform component; often used to describe a mixture with a consistent composition and a single phase throughout |
| liquid | liquid Liquid is a state of matter which has a fixed volume, but takes the shape of the container in which it is placed. |
| mixture | Mixtures consist of two or more substances that have been combined but in which each substance retains its own chemical identity. Mixtures can be homogeneous or heterogeneous. |
| nucleus (atom) | the core of an atom where most of the mass of an atom exists; contains protons and neutrons |
| phase of matter | Phases of ordinary matter are determined by pressure and temperature. For example, ice (solid) melts into water (liquid) due to the addition of heat. At high temperatures, or due to application of a magnetic field, matter becomes plasma. |
| physical property | Texture, color, melting and boiling point are are all characteristic physical properties. |
| plasma | A gas-like state of matter in which most of the particles are charged ions. |
| pure substance | a type of matter which has specific physical and chemical properties by which it can always be identified; can contain only kind of element, or one kind of compound |
| sedimentation | sedimentation Sedimentation is the settling of the particles of a mixture to the bottom of the mixture. Sedimentation can occur due to different agents such as gravity and centrifugal force. |
| solid | A solid's atoms or molecules are held together by strong bonds, giving the solid a fixed shape and volume. When liquid water freezes to form ice, it changes to a solid state. |
| solute | A solute is a substance that dissolves in a solvent to form a mixture. Salt dissolves in water to form a homogeneous mixture of saltwater. |
| solution | A solution is a mixture which consists of a solute dissolved in a solvent. In a sugar solution, sugar is the solute and water is the solvent. |
| solvent | A solvent is a substance that dissolves a solute to form a mixture. Water dissolves sugar to form a homogeneous sugar solution. |
| suspension | Suspensions are mixtures in which moderate sized particles are dispersed within a liquid or a gas. The particles in suspensions eventually settle to form a precipitate. |
| deposition (phase change) | Sea water contains dissolved minerals, such as salt (halite). When the water evaporates, the mineral precipitates in the form of halite crystals which are deposited on the rocks - the mineral halite has undergone a phase change from a liquid to a solid state. |
| boiling point | the temperature at which the vapor pressure of a liquid equals the pressure of the surrounding environment; . at this temperature, the liquid becomes a gas |
| condensation | the process by which a gas changes into a liquid |
| deposition (phase change) | Sea water contains dissolved minerals, such as salt (halite). When the water evaporates, the mineral precipitates in the form of halite crystals which are deposited on the rocks - the mineral halite has undergone a phase change from a liquid to a solid state. |
| evaporation | the process in which matter changes from a liquid to a gas |
| temperature | a measure of the average kinetic energy of the atoms in a system, used to express thermal energy in degrees |
| freezing | the change of state from liquid to solid |
| heat energy | a form of energy that transfers between particles in a substance or system through kinetic energy transfer |
| heating curve | a graph of temperature versus time for where heat is added at a constant rate and which shows the freezing and boiling points for a particular substance |
| intermolecular force | interactions that occur between molecules; London forces, dipole-dipole forces and hydrogen bonding are the three main types of intermolecular forces |
| kinetic energy | the energy an object has due to its motion |
| kinetic molecular theory | a theory that explains that the properties and actions of the particles making up a system affect the properties and actions of the entire system |
| liquid/vapor equilibrium | a state where a liquid and its gas are in equilibrium with each other |
| phase of matter | the physical forms in which matter exists, as determined by the average kinetic energy of the atoms involved; the most common phases of matter are solid, liquid, gas and plasma; also called state of matter; |
| potential energy | the amount of energy that is stored in an object; energy that an object has because of its position relative to other objects |
| state of matter | one of the four states in which matter exists – solid, liquid, gas or plasma |
| temperature | a measure of the average kinetic energy of the atoms in a system, used to express thermal energy in degrees |
| thermal energy | energy in the form of heat |
| vapor pressure | force exerted by a gas above a liquid in equilibrium |
| vaporize | process of converting a substance from its liquid or solid phase to its gas phase, through the application of heat; conversion directly from solid to gas is called sublimation |
| volume | the amount of space that an object occupies, measured in liters or centimeters cubed |
| Boyle’s law | the gas law that states that if the amount of a gas is fixed, the pressure and volume of the gas are inversely proportional |
| Charles's law | the gas law that states that if the amount of a gas is fixed, the temperature and volume of the gas are directly proportional |
| Dalton's law of partial pressures | the gas law that states that when a mixture of gases is present in a container, the pressure of each gas is independent of the others and is equal to what the pressure would be if the gas existed outside of the mixture |
| Graham's law of effusion | the gas law that states that the rate at which gas particles diffuse is dependent on their mass; the greater the molar mass of a gas’s particles, the more slowly the gas diffuses |
| Ideal Gas Law | relationship of pressure, volume, and temperature between free atoms or molecules |
| average kinetic energy | the average amount of movement of all the particles in a system; average kinetic energy is proportional to absolute temperature |
| combined gas law | the gas law that states that if the amount of a gas is held constant, the variables of temperature, pressure, and volume will change as described by Boyle’s law and Charles’s law when any one of the three variables is changed |
| diameter | the length of a straight line that runs from one side of a circle (or sphere) through the center of the circle (or sphere) to the other side; the width of a circle or sphere through its center |
| directly proportional | a relationship between two variables in which an increase in the value of one causes an increase in the value of the other |
| effusion | the movement of gas particles out of a container through a small opening |
| -ate | a suffix combined with the name of an element to designate polyatomic ions containing more oxygen atoms than similar ions |
| -ic | a suffix combined with the name of an element when naming multivalent metals; indicates a higher oxidation state than the –ous suffix |
| -ide | suffix placed at the end of an element's name to indicate that it is a negatively-charged ion |
| -ite | a suffix combined with the name of an element to designate polyatomic ions containing fewer oxygen atoms than similar ions |
| Aristotle | Greek philosopher, mathematician, natural scientist (384 BC – 322 BC), and a student of Plato; Aristotle’s ideas on the nature of the world dominated Western science for over 1500 years |
| Arrhenius acids and bases | the acid-base model in which an acid produces hydrogen ions (H+) and a base produces hydroxide ions (OH-) in solution |
| Aristotle's four elements | Aristotle believed that all earthly matter is composed of a combination of four elements, each with its own characteristics: Earth (cold and dry); Water (cold and wet); Fire (hot and dry) and Air (hot and wet). |
| Avogadro’s number | the number of particles in a mole, defined to be a quantity of 6.022 × 1023 |
| Boyle’s law | the gas law that states that if the amount of a gas is fixed, the pressure and volume of the gas are inversely proportional |
| Brønsted-Lowry acids and bases | the acid-base model in which an acid is a proton (H+) donor and a base is a proton (H+) acceptor |
| Charles's law | the gas law that states that if the amount of a gas is fixed, the temperature and volume of the gas are directly proportional |
| DNA | a molecule the contains the genetic coding necessary for reproduction of living cells |
| Dalton's law of partial pressures | the gas law that states that when a mixture of gases is present in a container, the pressure of each gas is independent of the others and is equal to what the pressure would be if the gas existed outside of the mixture |
| Democritus | Greek philosopher and natural scientist (460 BC – 370 BC) who formulated the philosophical idea that all matter is composed of small indivisible particles (atoms) residing in an empty space (the void) |
| Ernest Rutherford | New Zealand-born chemist and physicist (1871– 1937) known as "the father of nuclear physics"; Rutherford discovered the proton and formulated the Rutherford, or nuclear, model of the atom |
| Faraday’s Law | in an electrolytic cell, the amount of a substance that is consumed or produced at an electrode is proportional to the amount of electric current that passes through the electrolyte |
| Gibbs Free Energy | he energy associated with a chemical reaction that can be used to do work |
| Ideal Gas Law | relationship of pressure, volume, and temperature between free atoms or molecules |
| J.J. Thomson | British physicist (1856 1940) whose cathode ray tube experiment in 1897 showed that atoms were composed of smaller particles and led him to formulate the "plum pudding" model of the atom |
| John Dalton | British chemist and physicist (1766 1844) whose research about the properties of gases led to his development of modern atomic theory |
| Graham's law of effusion | the gas law that states that the rate at which gas particles diffuse is dependent on their mass; the greater the molar mass of a gas’s particles, the more slowly the gas diffuses |
| Heisenberg uncertainly principle | Werner Heisenberg discovered that the exact location and speed of an electron at cannot be determined at the same time |
| Hess's Law | states that the change in enthalpy (?H) during a chemical process is the same, regardless of how many steps the process takes |
| Le Chatelier's Principle | states that if an equilibrium is disturbed by changing the conditions (such as concentration, temperature, volume, or pressure), then the equilibrium moves to counteract the change and a new equilibrium is established |
| Lewis (electron) dot structure | a representation of an atom, ion, or molecule that uses the chemical symbol of an element to represent one atom and dots to represent one likely configuration of the valence electrons |
| Lewis acids and bases | according to Lewis acid-base theory, the electron pair donors and acceptors function as bases and acids in an acid-base reaction |
| London dispersion force | the intermolecular force between noble gas atoms or nonpolar molecules, created when an instantaneous dipole induces a dipole on neighboring atoms/molecules |
| Mendeleev | a Russian scientist who organized and classified the elements based on similar physical and chemical properties; his work was the basis for the modern periodic table of the elements |
| Nernst equation | an equation that relates the potential of an electrochemical cell to standard electrode potentials and effective concentrations |
| Niels Bohr | Danish physicist (1885 – 1962) who developed the orbital model of the atom, adding the idea of quantum energy levels to Rutherford's planetary model |
| Pauli Exclusion Principle | an important rule in quantum mechanics that states that no two electrons may have the same set of quantum numbers |
| Planck's constant | a fundamental physical constant equal to the energy of a quantum of radiation divided by its frequency (abbreviated "h") |
| Planck's wave equation | an equation that defines the relationship between the energy and frequency of a photon |
| RNA | ribonucleic acid (RNA): one of the macromolecules that determines protein synthesis in the cell |
| VSEPR theory | valence shell electron-pair repulsion (VSEPR) theory; states that the electron pairs in the valence shells of atoms repel each other, maximizing the angles between the atoms in the molecule |
| absorption | a physical process in which one substance takes in a given amount of another substance. |
| absorption spectra | a measurement of a given sample’s absorption of light as a function of wavelength/frequency; the information from this is specific to any element or compound, and can be used to identify unknown materials |
| acid | a substance that has a pH below 7; will increase the concentration of hydrogen ions in solution |
| acid dissociation constant (Ka) | the equilibrium constant for the ionization of an acid |
| actinide series | the elements following actinide (Ac, atomic number 89) that fill the 5f block from period 7 on the periodic table |
| activation energy | the minimum amount of energy required to initiate a chemical reaction; written as Ea and measured in kilojoules |
| alcohol | an organic compound that contains a hydroxyl group(-OH) in place of a hydrogen atom |
| aldehyde | an organic compound with a carbonyl group (=O) attached to a carbon at the end of a carbon chain |
| alkali metals | the group 1 (Group IA) elements: potassium (K), sodium (Na), lithium (Li), rubidium (Rb), cesium (Cs), and francium (Fr) |
| alkaline earth metals | the group 2 (Group IIA) elements: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) |
| alkane | an organic compound containing only single bonds between carbon and hydrogen atoms. |
| alkene | a organic compound containing at least one carbon-carbon double bond. |
| alkyne | an organic compound containing at least one carbon-carbon triple bond |
| alloy | a mixture of a metal and another element, either metal or nonmetal |
| alpha particle | a subatomic particle composed of two protons and two neutrons, represented by the symbol a |
