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| 256747359 | atomic theory | explanation of the structure of matter in terms of different combinations of very small particles | |
| 256747360 | atom | minute particle of which matter is composed; the smallest part of an element that can enter into chemical reaction | |
| 256747361 | compound | type of matter composed of atoms of two or more elements chemically combined in fixed proportions | |
| 256747362 | chemical reaction | rearrangement of atoms present in reacting substances to give new chemical combinations present in the substances formed | |
| 256747363 | law of multiple proportions | when two elements form more than one compound, the masses of one element in these compounds for a fixed mass of the other element are in ratios of small whole numbers | |
| 256747364 | atomic symbol | one- or two-letter notation used to represent an atom corresponding to a particular element | |
| 256747365 | nucleus | positively charged central core of an atom; contains most of the atom's mass | |
| 256747366 | electron | very light, negatively charge particle that exists in the region around the positively charged nucleus | |
| 256747367 | cathode | negative electrode | |
| 256747368 | anode | positive electrode | |
| 256747369 | cathode rays | rays that originate from the cathode, or negative electrode, in a gas-discharge tube | |
| 256747370 | coulomb (C) | unit of electric charge | |
| 256747371 | nuclear model | most of the mass of an atom is concentrated in a positively charged center, called the nucleus, around which negatively charge electrons move | |
| 256747372 | proton | nuclear particle having a positive charge equal to +e (e being the charge on an electron) and a mass more than 1800 times that of an electrons | |
| 256747373 | atomic number (Z) | number of protons in an atomic nucleus; identifies the element | |
| 256747374 | element | substance whose atoms all have the same atomic number | |
| 256747375 | neutron | neutral particle of mass almost identical to that of a proton, but without electric charge | |
| 256747376 | mass number (A) | total number of protons and neutrons in a nucleus | |
| 256747377 | nuclide | an atom characterized by a definite atomic number and mass number | |
| 256747378 | nuclide symbol | symbol for a nuclide in which the mass number is written as a superscript and the atomic number as a subscript on the left of the symbol for the element | |
| 256747379 | isotopes | atoms whose nuclei have the same atomic number but different mass number | |
| 256747380 | mass spectrometer | instrument used to determine atomic mass | |
| 256747381 | atomic mass unit (amu) | mass unit equal to exactly one-twelfth the mass of a carbon-12 atom | |
| 256747382 | atomic weight | average atomic mass for the naturally occurring element, expressed in atomic mass units | |
| 256747383 | mass spectrum | chart recording from the mass spectrometer that shows the relative number of atoms for various masses | |
| 256747384 | fractional abundance | fraction of the total number of atoms that is composed of a particular isotope | |
| 256747385 | periodic table | tabular arrangement of elements in rows and columns, highlighting the regular repetition of properties of the elements | |
| 256747386 | period (of periodic table) | elements in any one horizontal row of the periodic table | |
| 256747387 | group (or periodic table) | elements in any one column of the periodic table | |
| 256747388 | main-group (representative) elements | elements in the A groups of the periodic table | |
| 256747389 | transition elements | elements in the B groups of the periodic table | |
| 256747390 | inner-transition elements | two rows of elements at the bottom of the periodic table | |
| 256747391 | lathanides | first of the two rows of inner-transition elements | |
| 256747392 | actinides | second of the rows of inner-transition elements | |
| 256747393 | alkali metals | elements in Group IA of the periodic table | |
| 256747394 | halogens | elements in Group VIIA of the periodic table | |
| 256747395 | metal | substance or mixture that has a characteristic luster or shine and is generally a good conductor of heat and electricity; elemental metals are to the left of the staircase line on the periodic table | |
| 256747396 | malleable | able to be hammered into sheets | |
| 256747397 | ductile | able to be drawn into wire | |
| 256747398 | nonmetal | element to the right of the staircase line on the periodic table; exhibits characteristics different from those of metals | |
| 256747399 | metalloid (semimetal) | element bordering the staircase line on the periodic table; exhibits both metallic and nonmetallic properties | |
| 256747400 | semiconductors | elements that, when pure, are poor conductors of electricity at room temperature but become good conductors at higher temperatures | |
| 256747401 | doping | adding small amounts of other element to pure semiconductor elements to make them very good electrical conductors | |
| 256747402 | chemical formula | notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in the substance | |
| 256752086 | molecule | definite group of atoms that are chemically bonded together and, as a group, electrically neutral | |
| 256752087 | molecular substance | substance composed of molecules of all which are alike | |
| 256752088 | molecular formula | gives the exact number of different atoms of an element in a molecule | |
| 256752089 | structural formula | chemical formula that shows which atoms are bonded to one another in a molecule | |
| 256752090 | polymers | very large molecules that are made up of a number of smaller molecules repeatedly linked together | |
| 256752091 | monomers | the small molecules that are linked together to form a polymer | |
| 256752092 | ion | electrically charged particle obtained from an atom or chemically bonded group of atoms by addition or removal of one or more electrons | |
| 256752093 | anion | negatively charged ion | |
| 256752094 | cation | positively charged ion | |
| 256752095 | ionic compound | compound composed of cations and anions | |
| 256752096 | crystal | solid having a regular three-dimensional arrangement of either ions, atoms, or molecules | |
| 256752097 | formula unit | group of atoms or ions explicitly symbolized in the chemical formula | |
| 256752098 | organic compounds | molecular substance that contain carbon | |
| 256752099 | hydrocarbons | compounds containing only hydrogen and carbon | |
| 256752100 | functional groups | reactive portion of a molecule that undergoes predictable reaction | |
| 256752101 | alcohol | molecule that contains an —OH functional group | |
| 256752102 | ether | organic molecule that contains an oxygen atom between two carbon atoms | |
| 256752103 | chemical nomenclature | systematic naming of chemical compounds | |
| 256752104 | organic compounds | molecular substances that contain carbon combined with other elements, such as hydrogen, oxygen, and nitrogen | |
| 256752105 | inorganic compounds | compounds composed of elements other than carbon | |
| 256752106 | monatomic ion | ion formed from a single atom | |
| 256752107 | Stock system | system for naming compounds in which a Roman numeral within parentheses follows the first-named element ot indicate its charge or oxidation number | |
| 256752108 | oxidation stare or oxidation number | hypothetical charge assigned in accordance with certain rules; denoted with a Roman numeral following the name of the metal atom | |
| 256752109 | -ous | in an older system of nomenclature, a suffix added to the stem name of an element to indicate the cation of lower charge; also indicates the oxoacid with fewer oxygen atoms | |
| 256752110 | -ic | in an older system of nomenclature, a suffix added to the stem name of an element to indicate the cation of higher charge; indicates the oxoacid with more oxygen atoms; also indicates an acid solution obtained from binary compounds of hydrogen and nonmetals | |
| 256752111 | -ide | suffix added to the stem name of the element to name monatomic anions or the more electronegative element in binary compounds | |
| 256752112 | polyatomic ion | ion consisting of two or more atoms chemically bonded together and carrying a net electric charge | |
| 256752113 | oxoanion (oxyanion) | anion composed of oxygen with another element, which is the central element | |
| 256752114 | acid | molecular compound that can yield one or more hydronium ions, H3O+, an an anion for each acid molecule when the acid dissolves in water | |
| 256752115 | oxoacid | acid containing hydrogen, oxygen, and another element | |
| 256752117 | -ate | suffix denoting the oxoanion with the greater number of oxygen atoms | |
| 256752118 | -ite | suffix denoting the oxoanion with the lesser number of oxygen atoms | |
| 256752119 | hypo- | prefix denoting the oxoacid or oxoanion with the least number of oxygen atoms in the series | |
| 256752120 | per- | prefix denoting the oxoacid or oxoanion with the greatest number of oxygen atoms in the series | |
| 256752121 | acid anions | anions that have hydrogen atoms they can lose as hydronium ions, H3O+ | |
| 256752122 | di- | Greek prefix meaning two | |
| 256752123 | thio- | prefix meaning an oxygen in the root ion name has been replaced by a sulfur atom | |
| 256752124 | binary compound | compound composed of only two elements | |
| 256752125 | hydro- | prefix added to the stem name of the nonmetal to name the acid solution obtained from binary compound of hydrogen and nonmetals | |
| 256752126 | hydrate | compound that contains water molecules weakly bound in its crystals | |
| 256752127 | chemical equation | symbolic representation of a chemical reaction in terms of chemical formulas | |
| 256752128 | reactant | starting substance in a chemical reaction; appears to the left of the arrow in a chemical reaction | |
| 256752129 | product | substance that results form a chemical reaction; appears to the right of the arrow in a chemical equation | |
| 256752130 | coefficient | number that appears in front of a formula in a chemical equation and gives the relative number of molecules or formula units of a substance involved in the reaction | |
| 256752131 | (g) | phase label placed after a formula in a chemical equation to indicate that the substance is a gas | |
| 256752132 | (l) | phase label placed after a formula in a chemical equation to indicate that the substance is a liquid | |
| 256752133 | (s) | phase label placed after a formula in a chemical equation to indicate that the substance is a solid | |
| 256752134 | (aq) | phase label placed after a formula in a chemical equation to indicate that the substance is in aqueous (water) solution | |
| 256752135 | catalyst | substance that speeds up a reaction without undergoing any net change itself | |
| 256752136 | balanced | describes a chemical equation having correct coefficients | |
| 256752137 | balancing by inspection | trial-and-error method of balancing a chemical equation by writing appropriate coefficient until there is the same number of any one elemental atom on each side of the arrow |
