U of S. Carolina – Chemistry 105 – Test 2 – Flashcards
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| Name of Element that is Named After Mary Cluric |
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| Polonium |
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| Henri Becquerel (1896) |
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| Experimented with phosphorescence of certain materials (uranium) |
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| Earnest Rutherford (1899) |
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| Found that alpha rays could be stopped by thin pieces of paper. Whereas beta rays were only stopped by at least 0.5 cm of lead |
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| Paul Villard (1900) |
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| Discovered the high energy, extremely penetrating gamma ray having characteristics of light waves. Very damaging to human tissue |
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| Madame (Marie) Curie (1859-1906) |
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| Won the noble prize along with Henri Bacquerel for their work on radioactivity She discovered that some elements are more radioactive than others |
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| Radioactivity |
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| The result of a natural change of an isotope of one element into an isotope of a different element resulting in a nuclear reaction |
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| Nucleons |
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| Protons and Neutrons During a nuclear reaction the number of nucleons is conserved but the identity of the element changes by emitting a particle or a ray |
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| Alpha Emitters |
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| Radioactive decay of an atom resulting in the release of an Alpha particle ad changing the identity of the atom |
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| Alpha Particle |
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| Helium Nuclei (He) Decreases an element's electrons by 2 Decreases an element's atomic mass by 4 |
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| Beta Emitters |
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| Radioactive decay of an atom resulting in the release of a Beta particle and changing the identity of the atom |
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| Beta Particle |
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| An electron Adds 1 electron to an element |
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| Gamma Rays |
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| Highly energetic protons that is released by the excess energy remaining after a nucleus emits an alpha or beta particle |
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| Positron Emission |
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| A proton is converted to a neutron An element loses 1 electron |
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| Stability of Atomic Nuclei |
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| Based on relative number of protons and neutrons *Mass number as least twice as large as the atomic number (with the exception of Hydrogen isotopes) **When a greater neutron/proton ratio exists (beta decay occurs) **When a greater proton/neutron ratio exists (positron emission occurs) **For elements greater than atomic number 83 (alpha emission occurs decreasing the number of protons and neutrons by 2) |
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| Half Life |
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| The time required for exactly 50% of the original material to decay |
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| Radio Carbon Dating |
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| Determining the age of a sample using the carbon-14 isotope |
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| Gamma Rays (Applications of Radioactivity) |
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| From cobalt-60 and cesium-137 are used to irradiate food |
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| Food Radiation |
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| Retards the growth of organisms such as molds, bacteria, and yeasts |
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| Two Ways Radioactive Isotopes Are Used |
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| Diagnosis and Therapy |
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| Diagnosis |
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| Radioisotopes are inserted into the patients body allowing an image to be produced of the problem area |
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| Fission |
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| Large amounts of energy are released when heavy atomic nuclei split |
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| Fusion |
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| Large amounts of energy are released when small atomic nuclei are combined *Releases as much energy as fission with fewer radioactive by-products |
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| Octet Rule |
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| In forming bonds, main-group elements gain, lose, or share electrons to achieve a stable electron configuration with eight valence electrons |
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| Ionic Bond |
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| The attraction between positive and negative ions |
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| Ionic Compounds |
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| Compounds composed of positive and negative ions |
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| Formula Unit |
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| In ionic compounds, the simplest ratio of oppositely charged ions that gives an electrically neutral unit |
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| Lewis Dot Symbols |
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| The valence electrons, represented by dots, are placed around the symbol until they are used up or until all 4 sides are occupied **Can be used along with the octet rule to predict formulas for ionic compounds |
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| Binary Compound |
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| Chemical compound composed of one metal and one non-metal **Cation = metal = common name **Anion = non-metal = name ends in -ide Example: NaCl Sodium Chloride |
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| Polyatomic Ion |
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| A group of atoms with a net charge that behaves as a single particle |
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| Covalent Bond |
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| A bond in which 2 atoms share electrons to achieve a noble gas configuration |
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| Lewis Structure |
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| Electron dot representation of valence electrons in a molecule |
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| Bonding Pair |
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| Pair of electrons shared between 2 atoms in a molecule |
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| Nonbonding Pair |
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| Unshared pair of valence electrons in a molecule |
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| Hydrocarbons |
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| Compounds containing only carbon and hydrogen |
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| Alkanes |
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| Hydrocarbons with carbon-carbon single bonds |
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| Saturated Hydrocarbons |
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| Hydrocarbons that are alkanes |
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| Double Bond |
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| A bond in which 2 pairs of electrons are shared between atoms |
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| Triple Bond |
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| A bond in which three pairs of electrons are shared between atoms |
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| Electronegativity |
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| The ability of an atom to attract electrons toward itself **Increases from left to right on the periodic table and from top to bottom |
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| Non-Polar Bonding |
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| Describes a bond or molecule in which charge is evenly distributed, with no positive or negative regions |
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| Polar Bonding |
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| Describes a bond or molecule in which charge is unevenly distributed, creating positive and negative regions. Based on differences in electronegativity |
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| Shapes of Molecules |
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| Determined from the number of bonding pairs and the number of Ion pairs on the central atom |
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| Electrolyte |
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| A compound that conducts electricity when melted or dissolved in water |
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| Non-Electrolyte |
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| A compound that does not conduct electricity when melted or dissolved in water, or does not separate into ions in water |
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| Intermolecular Forces |
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| Attractive forces that act between molecules; weaker than covalent bonds |
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| Dipole-Dipole Forces |
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| Attractive forces between polar molecules |
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| London Dispersion Force |
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| *Very weak small molecules *Very strong large molecules *All molecules contain it |
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| Hydrogen Bonding |
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| Attraction between a hydrogen atom bonded to a highly electronegative atom (O,N,F) and an electronegative atom in another or the same molecule |
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| Solids |
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| Fixed shape and fixed volume, non-compressible, very strong intermolecular forces |
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| Liquids |
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| Variable shape but fixed volume, strong intermolecular forces, non-compressible |
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| Gases |
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| Variable shapes and volume, compressible, weak intermolecular forces |
