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| 61679866 | Absolute temperature | Temperature measured on the absolute scale, which has its origin at absolute zero. | |
| 61679867 | Absorption | The process of taking up by chemical or solvent action. | |
| 61679868 | Acid | A water solution that has an excess of hydrogen ions; it turns litmus paper red, has a sour taste, and neutralizes bases to form salts | |
| 61679869 | Acid Anhydride | A nonmetallic oxide that, when placed in water to form an acid solution | |
| 61679870 | Acid salt | A salt formed by replacing part of the hydrogen ions of a dibasic or tribasic acid with metallic ions. | |
| 61679871 | Actinide series | The series of radioactive elements starting with actinium, No. 89, and ending with lawrencium, No. 103. | |
| 61679872 | Activated Charcoal | A specially treated and finely divided form of carbon, which possesses a high degree of absorption. | |
| 61679873 | Adsorption | The adhesion (in an extremely thin layer) of the molecules of gases, of dissolved substances, or of liquids to the surfaces of solid or liquid bodies with which they come into contact. | |
| 61679874 | Alcohol | An organic hydroxyl compound formed by replacing one or more hydrogen atoms of a hydrocarbon with an equal number of hydroxyl groups. | |
| 61679875 | Aldehyde | An organic compound formed by dehydrating oxidized alcohol; contains the characteristic -CHO group. | |
| 61679876 | Alkali | Usually, a strong base, such as sodium hydroxide or potassium hydroxide. | |
| 61679877 | Alkyl | A substitutent obtained from a saturated hydrocarbon by removing one hydrogen atom. | |
| 61679878 | Allotropic forms | Forms of the same element that differ in their crystalline structures. | |
| 61679879 | Alloy | A substance composed of two or more metals, which are intimately mixed; usually by melting the metals together. | |
| 61679880 | Alpha particles | Positively charged helium nuclei. | |
| 61679881 | Alum | A double sulfate of a monovalent metal and a trivalent metal; also, a common name for commercial aluminum sulfate | |
| 61679882 | Amalgam | An alloy of mercury and another metal. | |
| 61679883 | Amine | A compound derived from ammonia by substituting one or more hydrocarbon radicals for hydrogen atoms. | |
| 61679884 | Amino acid | One of the "building blocks" of proteins; contains one or more NH₂- groups that have replaced the same number of hydrogen atoms in an organic acid. | |
| 61679885 | Amorphous | Having no definite crystalline structure. | |
| 61691621 | Amphoteric | Referring to a hydroxide that may have either acidic or basic properties, depending on the substance with which it reacts. | |
| 61691622 | Analysis | The breaking down of a compound into two or more simpler substances. | |
| 61691623 | Anhydride | A compound derived from another compound by the removal of water; it will combine with water to form an acid or a base. | |
| 61691624 | Anhydrous | Containing no water. | |
| 61691625 | Anion | An ion or particle that has a negative charge and thus is attracted to a positively charged anode. | |
| 61691626 | Anode | The electrode in an electrolytic cell that has a positive charge and attracts negative ions. | |
| 61691627 | Antichlor | A substance used to remove the excess of chlorine in the bleaching process. | |
| 61691628 | Aromatic compound | A compound whose basic structure contains the benzene ring; it usually has an odor. | |
| 61691629 | Atmosphere | The layer of gases surrounding the earth; also, a unit of pressure (1 atm=approx. 760 mm of Hg or torr). | |
| 61691630 | Atom | The smallest particle of an element that retains the properties of that element and can enter into a chemical reaction. | |
| 61691631 | Atomic mass | The average mean value of the isotopic masses of the atoms of an element. It indicates the relative mass of the element. | |
| 61691632 | Atomic mass unit | One twelfth of the mass of a carbon-12 atom; equivalent to 1.660531 x 10⁻²⁷ kilogram. | |
| 61691633 | Atomic number | The number that indicates the order of an element in the periodic system; numerically equal to the numbers of protons in the nucleus of the atom, or the number of negative electrons located outside the nucleus of the atom. | |
| 61691634 | Atomic radius | One-half the distance between adjacent nuclei in the crystalline or solid phase of an element; the distance from the atomic nucleus to the valence electrons. | |
| 61691635 | Aufbau Principle | The principle that states that an electron occupies the lowest energy orbital that can recieve it. | |
| 61691636 | Avogadro's number | The number of molecules in 1 gram-molecular volume of a substance, or the number of atoms in 1 gram-atomic mass of an element; equal to 6.022169 x 10²³. | |
| 61691637 | Barometer | An instrument, invented by Torricelli in 1643, used for measuring atmospheric pressure. | |
| 61800249 | Base | A water solution that contains an excess of hydroxide ions; a proton acceptor; it turns litmus paper blue and neutralizes acids to form salts. | |
| 61800250 | Basic anhydride | A metallic oxide that forms a base when placed in water. | |
| 61800251 | Beta particles | High-speed, negatively charged electrons emitted in radiation. | |
| 61800252 | Binary | Referring to a compound composed of two elements. | |
| 61800253 | Boiling point | The temperature at which the vapor pressure of a liquid equals the atmospheric pressure. | |
| 61800254 | Bonding | The union of atoms to form compounds or moleculesby filling their outer shells of electrons. This can be done through giving and taking electrons (ionic) or by sharing electrons (covalent). | |
| 61800255 | Brass | An alloy of copper and zinc. | |
| 61800256 | Breeder reactor | A nuclear reactor in which more fissionable material is produced than is used up during operation. | |
| 61800257 | Brownian movement | Continuous zigzagging movement of colloidal particles in a dispersing medium, as viewed through an ultramicroscope. | |
| 61800258 | Buffer | A substance that, when added to a solutioin, makes changing the pH of the solution more difficult. | |
| 61800259 | Calorie | A unit of heat; the amount of heat needed to raise the temperature of 1 gram of water 1 degree on the Celsius scale. | |
| 61800260 | Calorimeter | An instrument used to measure the amount of heat liberated or absobed during a change. | |
| 61800261 | Carbonated water | Water containing dissolved carbon dioxide. | |
| 61800262 | Carbon dating | The use of radioactive carbon-14 to estimate the ages of ancient materials, sich as archeological or paleontological specimens. | |
| 61800263 | Catalyst | A substance that speeds up or slows down a reaction without being permanently changed itself. | |
| 61800264 | Cathode | The electrode in an electrolytic cell that is negatively charged and attracts positive ions. | |
| 61800265 | Cathode rays | Streams of electrons given off by the cathode of a vacuum tube. | |
| 61800266 | Cation | An ion that has a positive charge. | |
| 61800267 | Celsius scale | A temperature scale divided into 100 equal divisions and based on water freezing at 0⁰ and boiling at 100⁰. Synonymous with centigrade. | |
| 61800268 | Chain reaction | A reaction produced during nuclear fission when at least one neutron from each fission produces another fission, so that the process becomes self-sustaining without additional external energy. | |
| 61801407 | Chemical change | A change that alters the atomic structures of the substances involved and results in diferent properties. | |
| 61801408 | Chemistry | The science concerned with the compositions of substances and the changes that they undergo. | |
| 61801409 | Colligative property | A property of a solution that depends primarily on the concentration, not the type, of particles present. | |
| 61801410 | Colloids | Particles larger than those found in a solution but smaller than those in a suspension. | |
| 61801411 | Combustion | A chemical action in which both heat and light are given off. | |
| 61801412 | Compound | A substance composed of elements chemically united in definite proportions by weight. | |
| 61801413 | Condensation | A change from gaseous to liquid state; the union of like or unlike molecules with the elimination of water, hydrogen chloride, or alcohol. | |
| 61801414 | Control rod | In a nuclear reactor, a rod of a certain metal such as cadmium, which controls the speed of the chain reaction by absorbing neutrons. | |
| 61801415 | Coordinate covalence | Covalence in which both electrons in a pair come from the same atom. | |
| 61801416 | Covalent bonding | Bonding accomplished through the sharing of electrons so that atoms can fill their outer shells. | |
| 61801417 | Critical mass | The smallest amount of fissionable material that will sustain a chain reaction. | |
| 61801418 | Critical temperature | The temperature above which no gas can be liquefied, regardless of the pressure applied. | |
| 61801419 | Crystalline | Having a definite molecular or ionic structure. | |
| 61801420 | Crystallization | The process of forming definitely shaped crystals when water is evaporated from a solution of the substance. | |
| 61801421 | Cyclotron | A device used to accelerate charged particles to high particles to high energies for bombarding the nuclei of atoms. | |
| 62228594 | Decomposition | The breaking down of a compound into simpler substances or into its constituent elements. | |
| 62228595 | Dehydrate | To take water from a substance. | |
| 62228596 | Dehydrating agent | A substance able to withdraw from another substance, thereby drying it. | |
| 62228597 | Deliquescence | The absorption by a substance of water from the air, so that the substance becomes wet. | |
| 62228598 | Denatured alcohol | Ethyl alcohol that has been "poisoned" in order to produce (by avoiding federal tax) a cheaper alcohol for industrial purposes. | |
| 62228599 | Density | The mass per unit volume of a substance; the mathematical formula is D=m/V, where D=?, m=mass, and V=volume. | |
| 62228600 | Destructive distillation | The process of heating an organic substance, such as coal, in the absence of air to break it down into solid and volatile products. | |
| 62228601 | Deuterium | An isotope of hydrogen, sometimes called heavy hydrogen, with an atomic weight of 2. | |
| 62228602 | Dew point | The highest temperature at which water vapor condenses out of the air. | |
| 62228603 | Dialysis | The process of separation of a solution by diffusion through a semipermeable membrane. | |
| 62228604 | Diffusion | The process whereby gases or liquids intermingle freely of their own accord. | |
| 62228605 | Dipole-dipole attraction | A relatively weak force of attraction between polar molecules; a component of van der Waals forces. | |
| 62228606 | Displacement | A change by which an element takes the place of another element in a compound. | |
| 62228607 | Dissociation | The separation of the ions of an ionic compound due to the action of a solvent. | |
| 62228608 | Distillation | The process of first vaporizing a liquid and then condensing the vapor back into a liquid, leaving behind the nonvolatile particles. | |
| 62228609 | Double bond | A bond between atoms involving two electron pairs. In organic chemistry: unsaturated. | |
| 62228610 | Double displacement | A reaction in which two chemical substances exchange ions with the formation of two new compounds. | |
| 62228611 | Dry ice | Solid carbon dioxide. | |
| 62228612 | Ductile | Capable of being drawn into thin wire. | |
| 62228613 | Effervescence | The rapid escape of excess gas that has been dissolved in a liquid. | |
| 62228614 | Efflorescence | The loss by a substance of its water of hydration on exposure to air at ordinary temperatures. | |
| 62228615 | Effusion | The flow of gas through a small aperture. | |
| 62228616 | EInstein equation | E=mc², which relates mass to energy; E=energy in ergs, m=mass in grams, and c=velocity of light, 3 x 10¹⁰ centimeters/second. | |
| 62228617 | Electrode | A terminal of an electrolytic cell. | |
| 68700611 | Electrode potential | The difference in potential between an electrode and the solution in which it is immersed. | |
| 68700612 | Electrolysis | The process of separating the ions in a compound by means of electrically charged poles. | |
| 68700613 | Electrolytic cell | A cell in which electrolysis is carried out. | |
| 68700614 | Electrolyte | A liquid that will conduct an electric current. | |
| 68700615 | Electron | A negatively charged particle found outside the nucleus of the atom; it has a mass of 9.109 x 10⁻²⁸. | |
| 68700616 | Electronegativity | The numerical expression of the relative strength with which the atoms of an element attract valence electrons to themselves; the higher the number, the greater the attraction. | |
| 68700617 | Electron volt | A unit for expressing the kinetic energy of subatomic particles; the energy acquired by an electron when it is accelerated by a potential difference of 1 volt; equals 1.6 x 10⁻¹² erg or 23.1 kilocalories/mole (abbreviation: eV). | |
| 68700618 | Electroplating | Depositing a thin layer of (usually) a metallic element on the surface of another metal by electrolysis. | |
| 68700619 | Element | One of the more than 100 "building blocks" of which all matter is composed. It consists of atoms of only one king and cannot be decomposed further by ordinary chemical means. | |
| 68700620 | Empirical formula | A formula that shows only the simplest ratio of the numbers and kinds of atoms. | |
| 68700621 | Emulsifying agent | A colloidal substance that forms a film about the particles of two immiscible liquids, so that one liquid remains suspended in the other. | |
| 68700622 | Emulsion | A suspension of fine particles or droplets of one liquid in another, the two liquids being immiscible in each other; the droplets are surrounded by a colloidal agent. | |
| 68700623 | Endothermic | Referring to a chemical reaction that results in an overall absorption of heat from its surroundings. | |
| 68700624 | Energy | The capacity to do work. In every chemical change it is either given off or taken in. | |
| 68700625 | Enthalpy | The heat content of a chemical system. | |
| 68700626 | Entropy | The measure of the randomness or disorder that exists in a system. | |
| 68700627 | Equation | A shorthand method of showing the changes that take place in a chemical reaction. | |
| 68700628 | Equilibrium | The point in a reversible reaction at which the forward reaction is occurring at the same rate as the opposing reaction. | |
| 68700629 | Erg | A unit of energy or work done by a force of 1 dyne (1/980 g of force) acting through a distance of 1 centimeter; equals 2.4 x 10⁻¹¹ kilocalorie. | |
| 68700630 | Ester | An organic salt formed by the reaction of an alcohol with an organic (or inorganic) acid. | |
| 68700631 | Esterification | A chemical reaction between an alcohol and an acid, in which an ester is formed. | |
| 68700632 | Ether | An organic compound containing the ⁻O⁻ group. | |
| 68700633 | Eudiometer | A graduated glass tube into which gases are placed and subjected to an electric spark; used to measure the individual volumes of combining gases. | |
| 68700634 | Evaporation | The process in which molecules of a liquid (or a solid) leave the surface in the form of vapor. | |
| 68700635 | Exothermic | Referring to a chemical reaction that results in the giving off of heat to its surroundings. | |
| 68700636 | Fahrenheit scale | The temperature scale that has 32° as the freezing point of water and 212° as the boiling point. | |
| 68700637 | Fallout | The residual radioactivity from an atmospheric nuclear test, which eventually settles on the surface of the earth. | |
| 68700638 | Filtration | The process by which suspended matter is removed from a liquid by passing the liquid through a porous material. | |
| 68700639 | Fission | A nuclear reaction that releases energy because of the splitting of large nuclei into smaller ones. | |
| 68700640 | Fixation of nitrogen | Any process for converting atmospheric nitrogen into compounds, such as ammonia and nitric acid. | |
| 68700641 | Flame | The glowing mass of gas and luminous particles produced by the burning of a gaseous substance. | |
| 68700642 | Flammable | Capable of being easily set on fire; combustible. | |
| 68700643 | Fluorescence | Emission by a substance of electromagnetic radiation, usually visible, as the immediate result of (and only during) absorption of energy from another source. | |
| 68700644 | Fluoridation | Addition of small amounts of fluoride (usually NaF) to drinking water to help prevent tooth decay. | |
| 68700645 | Flux | In metallurgy: a substance that helps to melt and remove the solid impurities as slag. In soldering: a substance that cleans the surface of the metal to be soldered. In nucleonics: the concentration of nuclear particles or rays. | |
| 68700646 | Formula | An expression that uses the symbols for elements and subscripts to show the basic makeup of a substance. | |
| 68700647 | Formula mass | The sum of the atomic mass units of all the atoms (or ions) contained in a formula. | |
| 68700648 | Fractional crystallization | The separation of the components in a mixture of dissolved solids by evaporation according to individual solubilities. | |
| 68700649 | Fractional distillation | The separation of the components in a mixture of liquids having different boiling points by vaporization. | |
| 68700650 | Freezing point | The specific temperature at which a given liquid and its solid form are in equilibrium. | |
| 68700651 | Fuel | Any substance used to furnish heat by composition. | |
| 68700652 | Fuel cell | A device for converting an ordinary fuel such as hydrogen or methane directly into electricity. | |
| 68700653 | Functional group | A group of atoms that characterizes certain types of organic compounds, such as ⁻OH for alcohols, and that reacts more or less independently. | |
| 68700654 | Fusion | A nuclear reaction that releases energy because of the union of smaller nuclei to form larger ones. | |
| 68700655 | Fusion melting | Changing a solid to the liquid state by heating. | |
| 68712256 | Galvanizing | Applying a coating zinc to iron or steel to protect the latter from rusting. | |
| 68712257 | Gamma rays | A type of radiation consisting of high-energy waves that can pass through most materials. | |
| 68712258 | Gas | A phase of matter that has neither definite shape nor definite volume. | |
| 68712259 | Gibbs free energy | Changes in it, ΔG, are useful in indicating the conditions under which a chemical reaction will occur. The equation is ΔG = ΔH - TΔS, where ΔH = change in enthalpy and ΔS = change in entropy. If ΔG is negative, the reaction will proceed spontaneously to equilibrium. | |
| 68712260 | Glass | An amorphous, usually translucent substance consisting of a mixture of silicates. Ordinary specimens are made by fusing together silica and sodium carbonate and lime; the various forms contain many other silicates. | |
| 68712261 | Gram | A unit of weight in the metric system; the weight of 1 milliliter of water at 4°C (abbreviation: g). | |
| 68712262 | Gram-atomic mass | The atomic mass, in grams, of an element. | |
| 68712263 | Gram-formula weight | The formula weight, in grams, of a substance. | |
| 68712264 | Group | A vertical column of elements in the periodic table that generally have similar properties. | |
| 68712265 | Half-life | The time required for half of the mass of a radioactive substance to disintegrate. | |
| 68712266 | Half-reaction | One of the two parts, either the reduction part or the oxidation part, of a redox reaction. | |
| 68712267 | Halogen | Any of the five nonmetallic elements (fluorine, chlorine, bromine, iodine, astatine) that form part of Group 17 of the Periodic Table. | |
| 68712268 | Heat | A form of molecular energy; it passes from a warmer body to a cooler one. | |
| 68712269 | Heat capacity | The quantity of heat, in calories, needed to raise the temperature of 1 gram of a substance 1 degree on the Celsius scale. | |
| 68712270 | Heat of formation | The quantity of heat either given off or absorbed in the formation of 1 mole of a substance from its elements. | |
| 68712271 | Heat of fusion | The amount of heat, in calories, required to melt 1 gram of a solid; for water, 80 calories. | |
| 68712272 | Heat of vaporization | The quantity of heat needed to vaporize 1 gram of a liquid at constant temperature and pressure; for water 100°C, 540 calories. | |
| 68712273 | Heavy water or Deuterium oxide or D₂O | Water in which the hydrogen atoms are replaced by atoms of the isotope of hydrogen, deuterium. | |
| 68712274 | Homogeneous | Uniform; having every portion exactly like every other portion. | |
| 68712275 | Homologous | Alike in structure; referring to series of organic compounds, such as hydrocarbons, in which each member differs from the next by the addition of the same group. | |
| 68712276 | Humidity | The amount of moisture in the air. | |
| 68712277 | Hybridization | The combination of two or more orbitals to form new orbitals. | |
| 68712278 | Hydrate | A compound that has water molecules included in its crystalline makeup. | |
| 68712279 | Hydride | Any binary compound containing hydrogen. | |
| 68712280 | Hydrogen bond | A weak chemical linkage between the hydrogen of one polar molecule and the oppositely charged portion of a closely adjacent molecule. | |
| 68712281 | Hydrolysis | Of carbohydrates: the action of water in the presence of a catalyst upon one carbohydrate to form simpler carbohydrates. Of salts: a reaction involving the splitting of water into its ions by the formation of a weak acid, a weak base, or both. | |
| 68712282 | Hydrogenation | A process in which hydrogen is made to combine with another substance, usually organic, in the presence of a catalyst. | |
| 68966362 | Hydronium | A hydrated ion, H₂O ⋅ H⁺ or H₃O⁺. | |
| 68966363 | Hydroponics | Growing plants without the use of soil, as in nutrient solution or in sand irrigated with nutrient solution. | |
| 68966364 | Hydroxyl | Referring to the -OH radical. | |
| 68966365 | Hygroscopic | Referring to the ability of a substance to draw water vapor from the atmosphere to itself and become wet. | |
| 68966366 | Hypothesis | A possible explanation of the nature of an action or phenomenon; it is not as completely developed as a theory. | |
| 68966367 | Immiscible | Referring to the inability of two liquids to mix. | |
| 68966368 | Indicator | A dye that shows one color in the presence of the hydrogen ion (acid) and a different color in the presence of the hydroxyl ion (base). | |
| 68966369 | Inertia | The property of matter whereby it remains at rest or, if in motion, remains in motion in a straight line unless acted upon by an outside force. | |
| 68966370 | Ion | An atom of a group of combined atoms that carries one or more electric charges. | |
| 68966371 | Ionic bonding | The bonding of ions due to their opposite charges. | |
| 68966372 | Ionic equation | An equation showing a reaction among ions. | |
| 68966373 | Ionization | The process in which ions are formed from neutral atoms. | |
| 68966374 | Ionization equation | An equation showing the ions set free from an electrolyte. | |
| 68966375 | Isomerization | The rearrangement of atoms in a molecule to form isomers. | |
| 68966376 | Isomers | Two or more compounds having the same percentage composition but different arrangements of atoms in their molecules and hence different proportions. | |
| 68966377 | Isotopes | Two of more forms of an element that differ only in the number of neutrons in the nucleus and hence in their mass numbers. | |
| 68966378 | IUPAC | International Union of Pure and Applied Chemistry, an organization that establishes standard rules for naming compounds. | |
| 68966379 | Joule | The SI unit of work or of energy equl to work done; 1 unit = 0.2388 calories, 1 calorie = 4.18 units. | |
| 68966380 | Kelvin scale | A temperature scale based on water freezing at 273 and boiling at 373 units; its origin is absolute zero. Synonymous with absolute scale. | |
| 68966381 | Kernel | The nucleus and all the electron shells of an atom except the outer one; usually designated by the symbol for the atom. | |
| 68966382 | Ketone | An organic compound containing the -CO- group. | |
| 68966383 | Kilocalorie | A unit of heat; the amount of heat needed to raise the temperature of 1 kilogram of water 1 degree on the Celsius scale. | |
| 68966384 | Kindling temperature | The temperature to which a given substance must be raised before it ignites. | |
| 68966385 | Kinetic-Molecular Theory | The theory that all molecules are in motion; this motion is most rapid in gases, less rapid in liquids, and very slow in solids. | |
| 68966386 | Lanthanide series | The "rare earth" series of elements starting with Lanthanum, No. 57, and ending with Lutetium, No. 71. | |
| 68966387 | Law | A generalized statement about the uniform behavior in natural processes. | |
| 68966388 | Avogadro's Law | Equal volumes of gases under identical conditions of temperature and pressure contain equal numbers of particles (atoms, molecules, ions, or electrons). | |
| 68966389 | Boyle's Law | The volume of a confined gas is inversely proportional to the pressure to which it is subjected, provided the temperature remains the same. | |
| 68966390 | Charles's Law | The volume of a confined gas is directly proportional to the absolute temperature, provided that the pressure remains the same. | |
| 68966391 | Conservation of Energy Law | Energy can be neither created nor destroyed, so that the energy of the universe is constant. | |
| 68966392 | Conservation of Matter Law | Matter can be neither created nor destroyed (or weight remains constant in an ordinary chemical change). | |
| 68966393 | Dalton's Law | When a gas is made up of a mixture of different gases, the pressure of the mixture is equal to the sum of the partial pressures of the components. | |
| 68966394 | Definite Composition Law | A compound is composed of two or more elements chemically combined in a definite ratio by weight. | |
| 68966395 | Faraday's Law | During electrolysis, the weight of any element liberated is proportional (1) to the quantity of electricity passing through the cell, and (2) to the equivalent weight of the element. | |
| 68966396 | First Law of Thermodynamics | The total energy of the universe is constant and cannot be created or destroyed. | |
| 68966397 | Gay-Lussac's Law | The ratio between the combining volumes of gases and the product, if gaseous, can be expressed in small whole numbers. | |
| 68966398 | Graham's Law | The rate of diffusion (or effusion) of a gas is inversely proportional to the square root of its molecular mass. | |
| 68966399 | Henry's Law | The solubility of a gas (unless the gas is very soluble) is directly proportional to the pressure applied to the gas. | |
| 68966400 | Hess's Law | If a series of reactions are added together, the enthalpy change for the total reaction is the sum of the enthalpy changes for the individual steps. | |
| 68966401 | Ideal Gas | Any gas that obeys the gas laws perfectly. No such gas actually exists. | |
| 68966402 | Multiple Proportions Law | When any two elements, A and B, combine to form more than one compound, the different masses of B that unite with a fixed mass of A bear a small whole-number ratio to each other. | |
| 68966403 | Periodic Law | The chemical properties of elements very periodically with their atomic numbers. | |
| 68966404 | Second Law of Thermodynamics | Heat cannot, of itself, pass from a cold body to a hot body. | |
| 68966405 | Le Châtelier's Principle | If a stress is placed on a system in equilibrium, the stem will react in the direction that relieves the stress. | |
| 69120458 | Lepton | An elementary particle; the electron and neutrino are believed to consist of these. | |
| 69120459 | Lewis dot symbol | The chemical symbol (kernel) for an atom, surrounded by dots to represent its outer level electrons. | |
| 69120460 | Liquid | A phase of matter that has a definite volume but takes the shape of the container. | |
| 69120461 | Liquid air | Air that has been cooled and compressed until it liquefies. | |
| 69120462 | Litmus | An organic substance, obtained from the lichen plant and used as an indicator; it turns red in acidic solution and blue in basic solution. | |
| 69120463 | London force | The weakest of the van der Waals forces between molecules. These weak, attractive forces become apparent only when the molecules approach one another closely (usually at low temperatures and high pressure). They are due to the way the positive charges of one molecule attract the negative charges of another molecule because of the charge distribution at any one instant. | |
| 69120464 | Luminous | Emitting a steady, suffused light. | |
| 69120465 | Malleable | Capable of being hammered or pounded into thin sheets. | |
| 69120466 | Manometer | A U-tube (containing mercury or some other liquid) used to measure the pressure of a confined gas. | |
| 69120467 | Mass | The quantity of matter that a substance possesses; it can be measured by its resistance to a change in position or motion, and is not related to the force of gravity. | |
| 69120468 | Mass number | The nearest whole number to the combined atomic mass of individual atoms of an isotope when that mass is expressed in atomic mass units. | |
| 69120469 | Mass spectograph | A device for determining the masses of electrically charged particles by separating them into distinct streams by means of magnetic deflection. | |
| 69120470 | Matter | A substance that occupies space, has mass, and cannot be created or destroyed easily. | |
| 69120471 | Melting | The change in phase of a substance from solid to liquid. | |
| 69120472 | Melting point | The specific temperature at which a given solid changes to a liquid. | |
| 69120473 | Meson | Any unstable, elementary nuclear particle having a mass between that of an electron and that of a proton. | |
| 69120474 | Metal | (a) An element whose oxide combines with water to form a base; (b) an element that readily loses electrons and acquires a positive valence. | |
| 69120475 | Metallurgy | The process involved in obtaining a metal from its ores. | |
| 69120476 | Meter | The basic unit of length in the metric system; defined as 1,650,763.73 times the wavelength of krypton-86 when excited to give off a orange-red spectral line. | |
| 69120477 | MeV | A unit for expressing the kinetic energy of subatomic particles; equals 10⁶ volts. | |
| 69120478 | Micron | One thousandth of a millimeter (abbreviation: μ). | |
| 69120479 | Mineral | An inorganic substance of definite composition found in nature. | |
| 69120480 | Miscible | Referring to the ability of two liquids to mix with one another. | |
| 69120481 | Mixture | A substance composed of two or more components, each of which retains its own properties. | |
| 69120482 | Moderator | A substance such as graphite, paraffin, or heavy water used in a nuclear reactor to slow down neutrons. | |
| 69120483 | Molal solution | A solution containing 1 mole of solute in 1,000 grams of solvent (indicated by m). | |
| 69120484 | Molar mass | The mass arrived at by the addition of the atomic masses of the units that make up a molecule of an element or compound. Expressed in grams/mole. | |
| 69120485 | Molar solution | A solution containing 1 mole of solute in 1,000 milliliters of solution (indicated by M). | |
| 69120486 | Mole | A unit of quantity that consists of 6.02 x 10²³ particles. | |
| 69120487 | Molecular mass | The sum of the masses of all the atoms in a molecule of a substance. | |
| 69120488 | Molecule | The smallest particle of a substance that retains the physical and chemical properties of that substance. | |
| 69120489 | Monobasic acid | An acid having only one hydrogen atom that can be replaced by a metal or a positive radical. | |
| 69120490 | Mordant | A chemical, such as aluminum sulfate, used for fixing colors on textiles. | |
| 69120491 | Nascent | Referring to an element in the atomic form as it has just been liberated in a chemical reaction. | |
| 69120492 | Neutralization | The union of the hydrogen ion of an acid and the hydroxyl ion of a base to form water. | |
| 69120493 | Neutron | A subatomic particle found in the nucleus of the atom; it has no charge and has the same mass as the proton. |
