Chem 109 – Chemistry – Flashcards
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Physical Process (Substances) |
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Transformation of a sample of matter, such as a change in its physical state, that does not alter the chemical identity of any substance in the sample |
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Mixture |
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Combination of pure substances in variable proportions in which the individual substances retain their chemical identities and can be separated from one another by a physical process |
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Homogeneous Mix |
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Mixture components uniformly distributed throughout |
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Solution (Homo Mix) |
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Another name for a homogenous mixture, often a liquid |
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Heterogeneous Mix |
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Mixture components are not distributed uniformly, containing distinct regions |
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Compound |
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Pure substance that is composed of two or more elements linked together in fixed proportions and that can be broken down to those elements by some chemical process |
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Element |
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Pure substance that cannot be separated into simpler substances by any chemical process |
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Atom |
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The smallest particle of an element that retains the chemical characteristics of the element |
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Molecule |
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A collection of atoms chemically bonded together in characteristic proportions |
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Chemical Formula |
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A notation for representing elements and compounds; consists of the symbols of the constituent elements and subscripts identifying the number of atoms of each element |
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Chemical Equation |
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Notation in which chemical formulas express the identities and their coefficients express the quantities of substances involved in a chemical reaction |
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Chemical Bond |
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The energy that holds two atoms in a molecule together |
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Filtration |
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A process for separating particles suspended in a liquid or a gas from that liquid or gas by passing the mixture through a medium that retains the particles |
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Solvent Extraction (Filtration) |
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Used to further filter particles by soaking the filter in a vial of solvent that dissolves many of the compounds present inside the phytoplankton cells |
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Thin Layer Chromatography (TLC) |
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A small volume of pigment extract is applied to the porous surface coating a thin plate, then the edge of the plate nearest the sample is immersed in a shallow bath of solvent, the solvent is drawn up the face of the plate by capillary action |
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Distillation |
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A separation technique in which the more volatile components of a mixture are vaporized and then condensed, thereby separating them from the less volatile components |
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Intensive Properties |
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A property that is independent of the amount of substance present (Pure Substances) |
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Extensive Properties |
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A property that varies with the quantity of the substance present |
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Physical Properties |
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A property of a substance that can be observed without changing it into another substance |
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Density |
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The ratio of the mass (m) of an object to its volume (V) |
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Chemical Property |
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A property of a substance that can be observed only by reacting it to form another substance |
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Scientific Method |
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An approach to acquiring knowledge based on observation of phenomena, development of a testable hypothesis, and additional experiments that test the validity of the hypothesis |
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Hypothesis |
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A tentative and testable explanation for an observation or a series of observations |
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Scientific Theory (model) |
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A general explanation of a widely observed phenomenon that has been extensively tested and validated |
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e = mc^2 |
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Energy (e) is equal to the equivalent of the mass of matter (m) times the speed of light (c) squared |
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Henri Lemaitre |
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Proposed the “Big Bang” in 1927 |
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Sir Fred Hoyle |
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Coined the term “Big Bang” |
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Robert Dicke |
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Predicted the cosmic microwave radiation of the universe |
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Meter |
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Predicted the cosmic microwave radiation of the universe |
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Significant Figures (Sig Figs) |
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All the certain digits in a measured value plus one estimated digit. The greater the number of significant figures, the greater the certainty with which the value is known |
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Addition & Subtraction of Sig Figs |
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The decimal position of the least significant digit is the weakest link and it determines the significant figures in the final answer |
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Multiplying & Dividing of Sig Figs |
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The significant figures of the answer are determined by the value with the fewest significant digits |
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Precision |
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The extent to which repeated measurements of the same variable agree |
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Accuracy |
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Agreement between an experimental value and the true value |
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Conversion Factors |
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A fraction in which the numerator is equivalent to the denominator but is expressed in different units, making the value of the fraction one |
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Conversion Factor Examples |
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o 1 ft = .3048 m o 1 km = .6214 mi o C* = 5/9 (F* - 32) |
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Kelvin (K) |
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The SI unit of temperature |
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Absolute Zero (0 K) |
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The zero point on the Kelvin temperature scale; theoretically the lowest temperature possible |
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Law of Constant Composition |
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All samples of a particular compound contain the same elements combined in the same proportions |
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Chemical Bond |
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The energy that holds two atoms in a molecule together |
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Wilson & Penzias |
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Received Nobel Prize in 1978 for actually discovering (in 1965) cosmic microwave radiation |
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Quarks |
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Tiny particles that initially condensed into neutrons. Neutrons with a half-life of 12 minutes began to decay into equal amounts of protons and electrons; come in 3 categories called "colors" (blue, green, red) for each color their are 6 "flavors" (up, down, strange, charmed, bottom, and top); are held together through the actions of particles called "gluons" |
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Subatomic Particles |
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The neutrons, protons, and electrons in an atom. In part discovered by J.J. Thomson as he determined the mass-to-charge-ratio (m/e) of electrons |
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Cathode Rays |
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Streams of electrons emitted by the cathode in a partially evacuated tube; used by J.J. Thomson to discover electrodes |
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Nucleo-Synthesis |
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Formation of the nuclei of elements in the early moments of the universe and later in the core of giant stars |
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Electrons |
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Subatomic particle that has a negative charge and essentially zero mass |
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Radioactivity |
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Spontaneous emission of high – energy radiation and particles by materials; discovered by Ernest Rutherford |
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Beta (B) Particles |
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A radioactive emission that is a high-energy electron |
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Alpha (a) Particles |
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A radioactive emission with a charge of 2+ and a mass equivalent to that of a helium nucleus |
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Robert Milikan |
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In 1909 determined the charge of electrons, allowing him to discover the mass |
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V0 (Terminal Velocity) (Milikan) |
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-k (constant based on air resistance) x m (mass of the drop) x g (acceleration due to gravity); Velocity is related to charge thru: v1 = k(Eq - mg); e1 = charge of an electron |
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Nucleus |
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The positively charged center of an atom that contains nearly all the atom’s mass; Hans Geiger and Ernest Mardsen, students of Rutherford, discovered the current understanding of atomic structure and dismissed the plum-pudding model |
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Protons |
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A positively charged subatomic particle present in the nucleus of an atom |
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Neutrons |
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An electrically neutral subatomic particle found in the nucleus of an atom; Another of Rutherford's student, James Chadwick discovered and isolated neutrons |
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Atomic Mass Units (amu) |
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Unit used to express the relative masses of atoms and subatomic particles that is exactly 1/12 the mass of one atom of carbon with 6 protons and 6 neutrons in its nucleus; |
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Daltons (Da) |
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A unit of mass identical to 1 atomic mass unit, also known as a unified atomic mass unit (u) |
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Ernest Rutherford |
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Debunked the “plum-pudding” model of an atom in 1907, leading to the discovery of the atomic nucleus |
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Rutherford Backscattering Spectrometry |
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Analytic technique using a beam of high-energy ions is directed at the sample of interest, most of the ions implant into the sample, but some of the ions will bounce back off of the sample (backscatter) due to interaction with the atomic nuclei in the sample. The number of backscattered ions can be used to find the square of the atomic number and thus, the identity of the target element. RBS is often used to measure the stoichiometry, or ratio of one element to another, of thin films; Something small, dense, and positively charged within the atoms caused the alpha particles to be repelled, it was the nucleus |
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# of Sub Atomic Particles |
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There are more than 40 sub-atomic particles, but none as important as the proton, neutron, and electron |
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Ions |
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An atom or group of atoms that has a positive or negative charge; Discovered by one of Thomson’s students, Francis W. Aston while using a positive-ray analyzer. Aston disproved John Dalton in that elements could have different masses |
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Isotopes |
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Atoms of an element containing the same number of protons but different number of neutrons |
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Nuclides |
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A specific isotope of an element |
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Atomic Number (z) |
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The number of protons in an atom |
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Nucleon |
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Either a proton or neutron in a nucleus |
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Mass Number (A) |
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The number of nucleons in an atom |
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Periodic Table of the Elements |
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- A chart of the elements in order of their atomic numbers, and in a pattern based on their physical and chemical properties |
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Average Atomic Mass |
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A weighted average of masses of all isotopes of an element, calculated by multiplying the natural abundance of each isotope by its mass in atomic mass units and then summing these products |
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Natural Abudnance |
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- The proportion of a particular isotope usually expressed as a percentage, relative to all the isotopes of that element in a natural sample |
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Dimitri Mendeleev |
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Published the forerunner to the modern periodic table in 1872. |
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Periods |
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The horizontal rows in the periodic table |
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Group (family) |
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All the elements in the same column of the periodic table |
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Halogen |
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An element in group 17 of the periodic table: "salt former" |
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Alkali Metal |
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An element in group 1 of the periodic table |
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Lanthanides |
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Elements in the row with atomic numbers from 58 to 71 |
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Actinides |
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Elements in the row with atomic numbers from 80 to 103; Most of the nuclides are radioactive, and none of those with the atomic number above 94 occur in nature |
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Alkaline Earth Metals |
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An element in group 2 of the periodic table |
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Metals |
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The elements on the left side of the periodic table that are typically shiny solids that conduct heat and electricity well and are malleable and ductile |
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Non-Metals |
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Elements with properties opposite those of metals including poor conductivity of heat and electricity |
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Metalloids and Semimetals |
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Elements along the border of the periodic table between metals and nonmetals; they have some metallic and some nonmetallic properties |
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Main Group Elements (Representative Elements) |
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The elements in groups 1, 2, and 13-18 of the periodic table; Include the most abundant elements in the solar system and many of the most abundant on Earth |
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Transition Metals |
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The elements in groups 3-12 of the periodic table; Nearly all classic metals |
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Noble Gasses |
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The elements in group 18 of the periodic table; Chemically unreactive, therefore elusive for early chemist; Missing on Mendeleev's table, as the first (Helium) was not discovered until 1895 |
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Dalton's Law of Multiple Proportions |
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The ratio of the two masses of one element that react with a given mass of another element to form two different compounds is the ratio of two small whole numbers |
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Molecular Compound |
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A compound composed of atoms held together in molecules by covalent bonds |
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Covalent Compound |
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A bond between two atoms created by sharing one or more pairs of electrons |
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Molecular Formula |
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A notation showing the number and type of atoms present in one molecule of a molecular compound |
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Ionic Compound |
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A compound composed of positively and negatively charged ions held together by electrostatic attraction; Each contains a metallic element combined with a nonmetal |
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Cation |
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Positively charged particle created when an atom or molecule loses one or more electrons; Atoms shrink when they lose an electron and expand when they gain one |
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Monatomic Ions |
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Single atoms with a positive/negative charge that form compounds |
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Anion |
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Negatively charged particle created when an atom or molecule gains one or more electrons |
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Empirical Formula |
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A formula showing the smallest whole-number ratio of elements in a compound |
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Formula Unit |
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The smallest electrically neutral unit of an ionic compound |
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Naming a Binary Ionic Compound |
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Start with the name of the cation, then add the name of the anion and change its ending to “ide”; Electrically neutral; Magnesium fluoride can only mean MgF2 |
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Naming Binary Compounds of Transition Metals |
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Use roman numerals to indicate the charge of the element, or “ous” to indicate the ion with the lower charge and “ic” to indicate the ion with the higher charge |
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Polyatomic Ions |
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Charged groups of two or more atoms joined together by covalent bonds |
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Ammonium |
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NH4+, the only polyatomic cation; all others are anions |
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Oxoanions |
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Polyatomic ions that contain oxygen in combination with one or more other elements; ? Names are usually based on the element that appears first in the formula, with the ending changed to either “ite” (lesser) or “ate” (greater) based on the # of oxygen atoms; ? Oxoanions with the largest number of oxygen atoms has the prefix “per” and that with the smallest has the prefix “hypo” |
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Acids |
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Compounds that release hydrogen ions (H+) when theAcids- Compounds that release hydrogen ions (H+) when they dissolve in water; their chemical formulas begin with H |
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Naming Acids |
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Affix the prefix “hydro” to the name of the element other than hydrogen, then replace the last syllable with “ic” and end with adding “acid” |
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Carboxylic Acids |
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An organic compound containing the –COOH functional group; Ionization of the hydrogen atom is the source of acidity in these compounds |
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Functional Group |
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A structural subunit in organic molecules that imparts characteristic chemical and physical properties |
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Organic Compound |
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Compounds containing carbon, and commonly including certain other elements such as hydrogen, oxygen, and nitrogen |
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Hydrogen & Helium |
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Two of the most abundant elements in the universe |
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(Primordial) Nucleosynthesis |
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The natural formation of nuclei as a result of fusion and other nuclear processes |
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Element Composition of the Early Universe |
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75% hydrogen, 25% helium for millions of years (it was too cold) |
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Carbon-12 |
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Initially created in the core of red giant stars through a “triple-alpha process” producing a nucleus with 6 p and 6 n; Carbon would then become the building block of Oxygen-16, Neon-20, and Magnesium-24 |
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Neutron Capture |
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The absorption of a neutron by a nucleus |
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Beta (B) Decy |
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The process by which a neutron decays into a proton and beta particle (0/-1 B) |
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