Chemistry 112 – Flashcards
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| Term |
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| Definition |
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| Chemistry |
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| The study of matter |
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| Matter |
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| Anything that has mass and volume |
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| Mass |
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| A measure of the gravitational force acting on an object |
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| Weight |
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| A measure of the mass of an object on Earth |
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| Physical Properties |
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| Properties that can be observed or measured without changing the composition of the matter |
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| Chemical Properties |
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| Properties observed when one attempts to change matter into some other type of matter |
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| Chemical Composition |
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| What chemicals are present |
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| Chemical Reactivity |
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| The ability to interact with other chemicals |
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| Physical Change |
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| A change in the state of matter (does not alter the chemical makeup) |
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| Chemical Change |
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| Substance changes into something new |
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| States of Matter |
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| Solid, Liquid, Gas |
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| Change of State |
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| Conversion of matter from one state to another |
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| Pure Substance |
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| Matter that is uniform in its chemical composition and properties |
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| Mixture |
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| A blend of two or more pure substances in any ratio, each retaining their identity |
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| Element |
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| Pure substance that cannot be broken down chemically into simpler substances |
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| Chemical Compounds |
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| Two or more elements combined chemically in specific ratios to form a pure substance |
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| Atom |
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| A single molecule of an element |
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| Molecule |
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| Two or more elements combined chemically in specific ratios to form a pure substance |
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| Chemical Formula |
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| A notation for a chemical compound using symbols and subscripts to show how many atoms of each element are present |
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| Physical quantities |
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| Measurements of physical properties such as height, volume and temperature requiring both a number and a unit |
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| SI Units |
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| Scientific standard set of units closely related to metric units |
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| Atomic Theory 1 |
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| All matter is composed of atoms |
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| Atomic Theory 2 |
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| The atoms of a given element differ from the atoms of all other elements |
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| Atomic Theory 3 |
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| Chemical compounds consist of atoms combined in specific ratios |
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| Atomic Theory 4 |
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| Chemical reactions change only the way the atoms are combined in compounds; the atoms themselves are unchanged |
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| Proton |
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| Subatomic particle with a positive charge |
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| Electron |
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| Subatomic particle with a negative charge |
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| Neutron |
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| Subatomic particle with no charge |
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| Nuclear strong force |
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| The force holding protons and neutrons together in an atom’s nucleus |
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| Mesons |
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| Exchanged between protons and neutrons creating nuclear strong force |
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| Atomic number |
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| (Z) – The number of protons in each atom of an element |
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| Mass Number |
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| (A)– The total number of protons and neutrons in a atom |
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| Isotopes |
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| Atoms with identical atomic numbers (Z) but different mass numbers (A); same number of protons, but varying number of neutrons |
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| Atomic Weight |
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| Average mass of an element and all of its naturally occurring isotopes |
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| Periodic Law |
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| When all the elements are placed in order of increasing atomic number, elements with similar chemical properties will occur at regular (periodic) intervals. |
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| Periods |
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| Seven horizontal rows of the periodic table |
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| Groups |
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| 18 vertical columns of the periodic table |
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| Main Groups |
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| The two groups on the far left (1&2) and the six on the far right (13-18) |
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| Transition Metal Groups |
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| Elements in groups 3-12 |
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| Inner Transition Metal Groups |
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| The 14 unnumbered groups shown at the bottom of the table |
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| Alkali metals |
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| Group 1 elements |
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| Alkaline earth metals |
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| Group 2 elements |
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| Halogens |
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| Group 7 elements |
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| Nobel Gases |
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| Group 8 elements |
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| Valence Electrons |
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| Electrons in the outermost shell of an atom |
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| Distinguishing Electron |
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| The last electron added to an element |
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| Electrically neutral |
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| All atoms of elements in the periodic table are this because they contain equal numbers of protons and electrons. |
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| Cation |
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| A positively charged ion due to the loss of one or more electrons |
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| Anion |
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| A negatively charged ion due to the gain of one or more electrons |
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| Ion |
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| An atom that has gained or lost one or more electrons and now has a charge |
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| Ionization energy |
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| The energy required to remove one electron from a single atom in the gaseous state |
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| Electron affinity |
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| The energy released on adding an electron to a single atom in the gaseous state |
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| First ionization energy |
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| The amount of energy required to remove the first electron from an atom |
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| Second ionization energy |
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| The amount of energy required to remove the second electron from an atom |
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| Ionic bond |
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| The electrical attractions between ions of opposite charge in a crystal |
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| Ionic compound |
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| A compound that contains ionic bonds |
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| Octet Rule |
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| After bonding, each atom will have 8 electrons in its valence shell |
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| Crystal lattice |
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| The most stable form of an ionic compound, a crystal of many ions in a rigid, three-dimensional arrangement |
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| Ionic solids |
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| Individual cation/anion bonds cannot be determined, therefore, collectively called this |
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| Polyatomic ions |
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| Ions that are composed of more than one atom |
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| Molecular weight |
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| The sum of the atomic weights for all the atoms in the molecule; the average mass of a substance’s molecules |
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| Formula weight |
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| The sum of the atomic weights for all the ions in the compound |
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| Covalent bond |
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| The bond formed when atoms share electrons |
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| Molecule |
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| A group of atoms held together by covalent bonds |
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| Repulsive interaction |
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| Like-charged atomic particles repel each other – nuclei and electrons |
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| Attractive interaction |
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| Oppositely charged atomic particles attract each other nucleus/electrons |
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| Single bond |
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| A covalent bond formed by sharing one electron pair |
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| Double bond |
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| A covalent bond formed by sharing two electron pairs |
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| Triple bond |
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| A covalent bond formed by sharing threre electron pairs |
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| Diatomic |
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| Two-atom molecules (H2, Cl2, N2, O2, F2, Br2, I2) |
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| Coordinate Covalent Bonds |
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| The covalent bond that forms when both electrons are donated by the same atom. This creates a charged molecule |
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| Molecular formula |
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| A formula that shows the numbers and kinds of atoms in one molecule of a molecular compound H2O |
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| Formula Unit |
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| The formula that identifies the smallest neutral unit in an ionic compound NaCl |
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| Structural formula |
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| A molecular representation that shows the connections among atoms by using lines to represent covalent bonds. H-O-H |
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| Polar covalent bonds |
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| In molecules of different elements, electrons are attracted more strongly by one atom that by the other and thus are shared unequally. |
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| Electronegativity |
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| The ability of an atom to attract electrons in a covalent bond |
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| Electronegativity difference <0.5 |
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| Covalent bonds |
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| Electronegativity difference >0.5 & <2.0 |
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| Increasingly polar covalent bonds |
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| Electronetativity difference > 2.0 |
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| Increasingly ionic bonds |
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| Intermolecular Forces |
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| Weak bonds that form between molecules (other than ionic and covalent) |
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| Dipole-dipole |
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| An intermolecular force where positive and negative ends of polar molecules are attracted to each other. This results in higher boiling points |
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| London dispersion forces |
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| Averaged over time, electron dispersion is uniform. A snap-shot in time may reveal more polarity of electrons and thus a momentary polarity to the molecule |
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| Reactant |
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| A substance that undergoes change in a chemical reaction and is written on the left side of the reaction arrow in a chemical equation |
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| Product |
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| A substance that is formed in a chemical reaction and is written on the right side of the reaction arrow in a chemical equation |
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| Law of Conservation of Mass |
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| Matter is neither created nor destroyed in chemical reactions. |
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| Combination/Addition reaction |
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| Molecules A and B combine/react to make C (A+B->C) |
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| Decomposition Reaction |
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| Molecule A breaks down into molecules B & C (A->B+C) |
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| Single Replacement |
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| One molecule replaces another (A+BC->AC+B) |
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| Double Replacement |
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| Both molecules break down and form new molecules (AB+CD->AC+BD) |
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| Mole |
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| The amount whose mass in grams is numerically equal to its molecular or formula weight |
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| Avogadro’s Number |
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| The number of molecules or formula units in a mole Na = 6.022 x 1023 |
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| Potential energy |
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| Stored energy ie a coiled spring |
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| Kinetic energy |
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| Energy in motion ie hands of the clock moving |
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| Bond dissociation energy |
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| The amount of energy that must be supplied to break a bond and separate the atoms in an isolated gaseous molecule |
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| Law of Conservation of energy |
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| Energy can be neither created nor destroyed in any physical or chemical change |
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| Heat of reaction |
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| The difference between the energy absorbed in breaking bonds and that released in forming bonds; represented by ?H |
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| Enthalpy change |
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| Heat of reaction |
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| Endothermic Process |
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| A chemical change (like bond breaking) that absorbs heat and has a positive ?H |
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| Exothermic Process |
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| A chemical change (like bond formation) that releases heat and has a negative ?H |
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| Spontaneous process |
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| A process that, once started, proceeds without any external influence |
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| Entropy |
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| A measure of the disorder of a system; ?S |
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| Free energy change |
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| Used to describe spontaneity of a process; ?G |
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| Exergonic |
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| A spontaneous reaction or process that releases free energy and has a negative ?G |
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| Endergonic |
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| A non-spontaneous reaction or process that absorbs free energy and has a positive ?G |
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| Activation energy |
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| The amount of energy/heat needed to start a reaction; Ea |
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| Catalyst |
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| A substance that accelerates a chemical reaction but is itself unchanged in the process |
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| Reversible reactions |
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| A reaction which easily goes in either direction; indicated by a double arrow in equations. |
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| Chemical equilibrium |
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| A state in which the rates of forward and reverse reactions are the same |
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| Le Chatelier’s Principle |
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| When a stress is applied to a system at equilibrium, the equilibrium shifts to relieve the stress. The stress can be any change in concentration, pressure, volume, or temperature that disturbs original equilibrium |
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| Kinetic-Molecular theory of gases #1 |
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| A gas consists of many particles, either atoms or molecules, moving about at random with no attractive forces between them |
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| Kinetic-Molecular theory of gases #2 |
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| The amount of space occupied by the gas particles themselves is much smaller than the amount of space between particles. |
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| Kinetic-Molecular theory of gases #3 |
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| The average kinetic energy of gas particles is proportional to the Kelvin temperature |
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| Kinetic-Molecular theory of gases #4 |
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| Collisions of gas particles, either with other particles or with the wall of their container, are elastic; that is, the total kinetic energy of the particles is constant |
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| Ideal Gas |
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| A gas that obeys all the assumptions of the kinetic-molecular theory |
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| Boyle’s law |
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| The volume of a gas is inversely proportional to its pressure for a fixed amount of gas at a constant temperature – More pressure, less volume, same temp. |
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| Charles’s law |
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| The volume of a gas is directly proportional to its Kelvin temperature for a fixed amount of gas at a constant pressure. – More heat, more volume, same pressure |
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| Gay-Lussac’s law |
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| The pressure of a gas is directly proportional to its Kelvin temperature for a fixed amount of gas at a constant volume. – More heat, more pressure, same volume |
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| Avogadro’s law |
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| The volume of a gas is directly proportional to its molar amount at a constant pressure and temperature |
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| Dalton’s law |
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| The total pressure exerted by a gas mixture is the sum of the partial pressures of the components in the mixture. |
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| Vapor |
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| A molecule near the surface of a liquid can break free of the liquid and escape into this gaseous state |
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| Vapor pressure |
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| The contribution that the gas molecules make to the total pressure of the gas above the liquid according to Dalton’s law |
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| Boiling |
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| Bubbles of vapor form under the surface and force their way to the top of the liquid |
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| Surface tension |
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| The resistance of a liquid to spread out and increase its surface area; caused by the difference between the forces experienced by molecules at the surface and these experienced by molecules in the interior. |
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| Specific heat |
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| The capacity to absorb a large quantity of heat while changing only slightly in temperature |
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| Heat of vaporization |
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| The ability of water to carry away a large amount of heat with it evaporates |
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| Bronsted-Lowry acid |
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| Any substance that is able to give a hydrogen ion to another molecule or ion, and need not occur in water |
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| Bronsted -Lowry base |
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| a substance that accepts a hydrogen ion from an acid, and need not occur in water |
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| Amphoteric |
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| Substances like water, which can react as either an acid or a base depending on the circumstances. |
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| Dissociation |
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| The splitting apart of an acid in water to give H+ and an anion |
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| pH |
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| A measure of the acid strength of a solution; the negative common logarithm of the H3O+ concentration |
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| Buffer |
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| A chemical reaction that keeps hydrogen ions from getting too high |
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| Nuclear reaction |
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| A reaction that changes an atomic nucleus, usually causing the change of one element into another |
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| Nuclear decay |
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| The spontaneous emission of a particle from an unstable nucleus |
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| Transmutation |
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| The resulting change of one element into another |
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| Alpha emission |
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| The emission of 2 protons and 2 neutrons as an ? particle from an unstable radioactive nucleus, resulting in a positive charge |
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| Beta emission |
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| The result of a neutron decomposing into a proton and an electron, retaining the proton in the nucleus and emitting the electron as a ? particle, resulting in a negative charge |
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| Gamma emission |
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| The emission of photons which have no charge |
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| Positron emission |
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| The conversion of a proton in the nucleus into a neutron plus an ejected positron, a ‘positive electron,” which has the same mass as an electron but a positive charge |
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| Electron Capture |
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| A process in which the nucleus captures an inner-shell electron from the surrounding electron cloud, thereby converting a proton into a neutron. |
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| Half-life |
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| The amount of time required for one-half of the radioactive sample to decay |
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| Nuclear fission |
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| The fragmenting of heavy nuclei |
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| Nuclear fusion |
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| The joining together of light nuclei |
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| Chain reaction |
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| A reaction that is self-sustaining |
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| Critical Mass |
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| The minimum amount of radioactive material needed to sustain a nuclear chain reaction |
