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Ch2 Flashcards

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Termini in questo insieme (29)

  • 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 atoms of 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 is 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 experiments.
  • Millikan Oil-Drop Experiment
    Measured the charge of the electron as 1.602 x 10-19 C, 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
    Model of the atom as a positive sphere with embedded negative electrons.
  • Rutherford's Gold Foil Experiment
    Discovered the nucleus by observing deflection of alpha particles, showing atoms have a small, dense positive center.
  • Modern Atomic Structure
    Atoms consist of a dense nucleus with protons and neutrons, surrounded by electrons in mostly empty space.
  • Subatomic Particles
    Protons (+1 charge), neutrons (neutral), and electrons (-1 charge); protons and neutrons have similar mass, electrons much smaller.
  • 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 the same number of protons but different numbers of neutrons.
  • Atomic Mass Unit (amu)
    Unit of atomic mass; 1 amu = 1.66053907 x 10-24 g, based on carbon-12 mass.
  • 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 (periods) and columns (groups) with similar chemical properties.
  • Groups in the Periodic Table
    Columns with elements sharing chemical properties; notable groups include alkali metals, alkaline earth metals, halogens, and noble gases.
  • Metals vs Nonmetals
    Metals are shiny, conductive solids (except mercury); nonmetals vary in state and are on the right side of the periodic table.
  • Metalloids
    Elements along the stair-step line with properties intermediate between metals and nonmetals.
  • 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 of atoms; 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 from metals and nonmetals by transfer of electrons; compounds are electrically neutral with empirical formulas.
  • 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.