Key Vocabulary Terms & People – Flashcards
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Chemistry |
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The study of the composition and properties of substances and the changes that such substances can undergo. |
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Scientific Method |
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Orderly adn systematic approach to gathering information in order to answer questions about the world. |
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Observation |
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Fact that is noticed either qualitatively or quantitatively, usually as an early part of the scientific method. |
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Hypothesis |
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Proposed, but unproved, explanation of observed facts. |
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Experiment |
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Carefully devised procedure for making observations and gathering data. |
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Conclusion |
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Judgment or opinion formed as a result of analyzing experimental data. |
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Natural Law |
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Description of a phenomenon that has been repeatedly and uniformly observed in nature. |
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Theory |
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Logical and time-tested explanation of a phenomenon that occurs in the natural world. |
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Variable |
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Factor being tested in an experiment |
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Experimental Control |
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Fasctor that ramains consstatn during an experiment and is compared with the variable. |
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Metric System |
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Deximal system of measurement used interenationallly |
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Mass |
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Quantity of matter in an object |
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volume |
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amount of space that an object occupies |
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density |
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mass of an object divided by its volume. |
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Matter |
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anything that has mass and volume |
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solid |
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state in which matter holds a definate shape and volume. |
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Liquid |
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state in which matter does not hold a definite shape but occupies a definite volume. |
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Gas |
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state in which matter has no definite shape or volume. |
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Physical Property |
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characteristic of a substance that can be ovserved without altering the identy of a substance. |
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Chemical Property |
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Characteristics of a substance that cannot be observed without altering the identy of a substance. |
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Mixture |
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blend of two or more pure substances that are not chemically combined. |
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Homogeneous Mixture |
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Mixture made up of uniformly intermingled particleas that therefore dose not contain visibly different parts. |
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Heterogeneous Mixture |
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Mixtuer in which the particles are nto uniformly intermingled and that therefore has visibly different parts. |
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Atom |
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Smallest particle of an element that retains teh chemical identity of the element. |
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Atomic Theory of Matter |
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theory proposed by John Dalton stating that elements are composed of atoms, all atoms of a given element are identical but different from atoms of other elements, atoms are neither created nor destroyed in a chemical reaction. |
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Electron |
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negatively charged particle within an atom |
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Radioactivity |
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spontaneous emission of radiation from an atom |
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nucleus |
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concentrated core of an atom, which contains protons and neutrons. |
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Proton |
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positively charged particle within the nucleus of an atom |
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Neutron |
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natural particle within the nucleus of an atom |
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Atomic Number |
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number of protons in the nucleus of an atom |
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Ion |
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a group that has a positive or negative charge because it has lost or gained electrons. |
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isotope |
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atom athat has the same number of protons as another atom, but different number of neutrons. |
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Mass Number |
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sum of the number of protons and neutrons in teh nucleus of a given atom |
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atomic mass |
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weighted average of the mass of the existing isotopes of an element. |
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Electromagnetic Radiation |
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form of energy consisting of waves made up of oscillations electric and magnetic fields at right angles to each other. |
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Amplitude |
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height of a wave measured from its orgin to its crest. |
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Wavelength |
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Distance between tow successive similar points on a wave |
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frequency |
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number of waves that pass a fiven point in a certain regions of an atom |
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speed of light |
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3.00x10^8 ms |
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Quantum |
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discrete bit of energy; smallest unit of radiant energy that can be emitted or absorbed |
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Photoelectric Effect |
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Phenomenon in which light can be used to knock electrons out of a metal |
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Photon |
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quantum of electromagnetic energy |
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Orbit |
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term used to describe the probability of finding electrons in certain regions of an atom. |
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sublevel |
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division of principle energy levels in an atom |
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electron configuration |
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distribution of electrons among the orbitals of an atom |
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Orbital diagram |
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representation of an atom in which arrows in boxes are used to show the elextron configuration of an atom. |
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Periodic Table |
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Arrangement of elembents in order of their atomic numbers so that elements with similar electron configurations are located in teh same column. |
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GroupFamily |
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Verticle column ofthe periodic table |
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Period |
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Horizontal row of elements in the periodic table. |
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Alkali Metal |
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element in group 1A |
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Alkali Earth Metal |
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elements in group 2A |
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Halogen |
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reactive, non-metal in group 7A |
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Noble Gas |
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inactive element in group 8A |
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Metal |
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Element that typically has a high melting point, is ductile, malleable, shiny, and good conductor of heat and electricity. |
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Non-Metal |
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element that has a low melting point and a dull surface, breaks easily, is a poor conductor of heat and elextricity, and tends to gain elextrons in chemical reactions. |
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SemimetalMetalloid |
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element ahtt does not have a metallic properties; found on the right side fo the periodic table |
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valence electron |
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electrons in the outermost energy level of an atom |
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electronegativity |
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property of an element that indicates how strongly an atom of that element attracts electrons in a chemical bond |