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General Chemistry: Atomic Structure and Nomenclature

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  • Dalton's Atomic Theory - Postulate 1

    Each element is composed of extremely small particles called atoms.
  • Dalton's Atomic Theory - Postulate 2

    All atoms of a given element are identical in mass and properties, but differ from atoms of other elements.
  • Dalton's Atomic Theory - Postulate 3

    Atoms are neither created nor destroyed in chemical reactions; atoms of one element cannot change into another.
  • Dalton's Atomic Theory - Postulate 4

    Atoms of different elements combine in fixed ratios to form compounds with the same relative number and kind of atoms.
  • Law of Conservation of Mass

    The total mass of substances before and after a chemical process remains constant.
  • Law of Constant Composition

    Compounds have a definite composition with the same relative number of atoms of each element in any sample.
  • Law of Multiple Proportions

    If two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers.
  • Discovery of the Electron

    J. J. Thomson discovered the electron as a negatively charged particle in 1897 using cathode ray tubes.
  • Millikan Oil-Drop Experiment

    Measured the charge of the electron as 1.602 x 10-19 coulombs, allowing calculation of electron mass.
  • Radioactivity

    Spontaneous emission of high-energy radiation by atoms, discovered by Henri Becquerel and studied by Marie and Pierre Curie.
  • Types of Radioactive Radiation

    Alpha (α) particles are positive, beta (β) particles are negative, and gamma (γ) rays are uncharged.
  • Thomson's Plum Pudding Model

    Atom modeled as a positive sphere with embedded negative electrons, later disproved by Rutherford's experiments.
  • Rutherford's Gold Foil Experiment

    Discovered the nucleus by observing deflection of alpha particles, showing atoms have a small, dense positive center.
  • Subatomic Particles and Charges

    Protons (+1), neutrons (neutral), and electrons (-1) make up atoms; protons and neutrons are in the nucleus.
  • Atomic Number

    Number of protons in the nucleus; defines the element and equals the number of electrons in a neutral atom.
  • Isotopes

    Atoms of the same element with different numbers of neutrons and different mass numbers.
  • Atomic Mass Unit (amu)

    Unit of atomic mass; 1 amu = 1.66053907 x 10-24 g, based on 1/12 the mass of a carbon-12 atom.
  • Atomic Weight

    Weighted average mass of an element's isotopes based on their natural abundance.
  • Periodic Table Organization

    Elements arranged by increasing atomic number in rows called periods and columns called groups with similar properties.
  • Groups and Their Names

    Examples: Group 1A - Alkali metals, 2A - Alkaline earth metals, 6A - Chalcogens, 7A - Halogens, 8A - Noble gases.
  • Metals, Nonmetals, and Metalloids

    Metals are shiny, conductive solids; nonmetals vary in state; metalloids have mixed properties and lie along the stair-step line.
  • Chemical Formula

    Shows the number of atoms of each element in a molecule using subscripts.
  • Diatomic Molecules

    Seven elements naturally exist as diatomic molecules: H2, N2, O2, F2, Cl2, Br2, I2.
  • Empirical vs Molecular Formulas

    Empirical formulas show the lowest whole-number ratio; molecular formulas show the exact number of atoms.
  • Ions

    Atoms that gain electrons become anions (negative), and atoms that lose electrons become cations (positive).
  • Ionic Compounds

    Formed by transfer of electrons between metals and nonmetals; composed of cations and anions held by electrostatic attraction.
  • Naming Ionic Compounds

    Name the cation first, then the anion; use Roman numerals for cations with multiple charges; anions end with -ide or use polyatomic ion names.
  • Naming Binary Molecular Compounds

    Use prefixes to denote number of atoms; the element farther left or lower in the group is named first; second element ends with -ide.
  • Nomenclature of Acids

    If anion ends in -ide, acid name starts with hydro- and ends with -ic acid; -ite anions form -ous acids; -ate anions form -ic acids.