general chemistry 2 reviewer

• Johann Wolfgang Dobereiner


  Law of Triads: when elements are arranged in increasing order of their atomic masses, the arithmetic mean of the atomic masses of the first and third element in a triad is approximately equal to the atomic mass of the second element in that triad
• John A.R. Newlands


  Arranged the 56 known elements into a periodic table with increasing order of atomic masses, found that every eight elements had similar properties and called this the law of octaves
• Dmitry Mendeleev


  Published the first version of a systematically organized periodic table of elements, arranged in order of increasing atomic mass, organized the elements in columns called groups or families, and rows called periods or series
• Henry Moseley


  Arranged the elements in the periodic table according to atomic numbers
• Groups


  • IA Alkali Metals
  • IIA Alkaline Earth Metals
  • Transition Metals
  • IIIA Boron Group
  • IVA Carbon Group
  • VA Nitrogen Group
  • VIA Oxygen Group
  • VIIA Halogen Group
  • VIIIA Noble Gas Group
• Periods


  • Period 1
  • Period 2
  • Period 3
  • Period 4
  • Period 5
  • Period 6 Lanthanide
  • Period 7 Actinide
• Period 1


  Has two elements corresponding to the two electrons in the s sublevel
• Period 2 & 3


  Have eight elements corresponding to eight electrons in the s and p sublevels
• Period 4 & 5


  Have 18 elements corresponding to 18 electrons in the s, p, and d sublevels
• Period 6 & 7


  Have 32 elements corresponding to 32 electrons in the s, p, d, and f sublevels
• Valence electron


  Electrons in the outermost shell
• To find period


  Always look to the highest coefficient in the electronic configuration
• To find group


  Always look the subscript of the highest coefficient
• Blocks


  • s block
  • p block
  • d block
  • f block
• Valence electron/outer electronic configuration


  Equals group number
• Occupied main energy level


  Equals period number
• Types of elements


  • Metals
  • Nonmetals
  • Metalloids
• Metals


  Atoms tend to lose or donate electrons, have higher melting point and electrical conductivity, luster, density, malleability, and ductility compared to nonmetals
• Nonmetals


  Atoms are structured to accept electrons, located in the rightmost part of the periodic table
• Metalloids


  Elements in the borderline of the metals and nonmetals, share properties of both
• Formation of Cations and Anions


  One or more electrons are removed or added, respectively, from/to the highest occupied energy level in order to have a stable outer configuration of electrons (with 8 valence electrons)
• Valence


  • Group 1A exhibits +1
  • Group 2A exhibits +2
  • Group 3A exhibits +3
  • Group 5A exhibit -3
  • Group 6A exhibit -2
  • Group 7A exhibit -1
  • Group 8A have 8 valence electrons and not expected to give up/take electrons
• Periodic Trends


  Specific patterns that are present in the periodic table that illustrate different aspects of a certain element

  
• To Left & To Down


  Bigger / Increases
• To Right & To Up


  Smaller / Decreases
• Atomic Size


  Atomic radius, the distance from the center of the nucleus to the outermost shell containing electrons
• Ionic Radius


  The distance between the nucleus and the electron in the outermost shell of an ion, many electrons = bigger, less electrons = smaller
• Ionic Size


  When a neutral atom loses or gains electrons, the nuclear charge remains the same but the electron-electron repulsion changes, all cations are smaller than their corresponding atoms, and all anions are bigger than their corresponding atoms
• Metallic Property


  The ability of the atom to donate electrons, the smaller the number of valence electrons and the farther they are from the nucleus, the greater the metallic property
• To Right & To Up


  Smallest / Increases
• To Left & To Down


  Biggest / Decreases
• Ionization Energy


  Energy required to remove an electron from its orbital around an atom, a greater distance between the valence electron and the nucleus means weaker attraction (easier to remove electrons), a closer distance to the nucleus means stronger attraction
• Electron Affinity


  The energy given off when an electron is added to a neutral atom in the gaseous state, the greater the electron affinity, the greater the affinity or "attraction" of an atom for an electron
• Electronegativity


  Measure the tendency of an atom to attract bonding pair of electrons
• Octet Rule


  States that atoms tend to form compounds in ways that give them eight valence electrons
• Exceptions to the Octet Rule


  • Incomplete octet
  • Odd number of electrons (odd-electron molecules/radicals)
  • Expanded Octet
• Ionic Bond


  Formed between a metal and a nonmetal, involving the transfer of valence electron(s)
• Properties of Ionic Substances


  • Form crystalline solids, have high melting and boiling points, are hard and brittle
• Chemical Bond


  The force of attraction that holds two atoms together in a molecule or ion pair, formed either by transferring or sharing of electrons to achieve a stable configuration similar to the noble gases
• Lewis Dot Symbol


  Used in demonstrating the bond formation, consists of the symbol of the element and a dot equal to the number of its valence electrons