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Ch 222 Exam #1 Outline Winter 2011 Ch 8 – Periodic Relationships Among the Elements Mendeleev and the Periodic Law Representative elements, Noble gases, Transition elements, f-block transition elements valence electrons – representative vs. transition metals electron configurations of cations and anions (transition metals s-electrons removed first) shielding and effective nuclear charge (nuclear charge effect) periodicity in atomic radius, ionic radius, ionization energy, and electron affinity Ch 9 – Chemical Bonding I: Basic Concepts Lewis dot symbols Lewis structures for ionic compounds Lattice energies, Coulomb's Law, and Born-Haber cycles Lewis structures for covalent compounds, single, double, and triple bonds Bond lengths properties of covalent vs. ionic compounds polar covalent compounds trends in electronegativity predicting polar covalent vs. ionic bonds Lewis structures for charges species formal charge guidelines for drawing Lewis structures including (1) selecting a central atom with the lowest electronegativity, (2) choosing a structure with the least formal charge on each atom, (3) choosing a structure where the lowest formal charge is on the most electronegative atom drawing resonance structures (hybrids) Exceptions to the Octet Rule: (1) less than 8 valence electrons for Group 3A, (2) expanded octets when the central atom is in the 3rd period or higher (exccpt for charged polyatomic ions mentioned in the major exception above), (3) odd-electron species (free radicals) bond energies and calculation of Horxn Ch10 on the back Ch 10 – Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals VSEPR Geometry (A = central atom, B = terminal atom, E = lone pair) Electron Cloud Geometry Linear Trigonal planar Tetrahedral Trigonal Bipyramidal NOTE: lone pairs are equatorial Octahedral Bond Angles 180o 120o 109.5o equatorial = 120o, apical = 90o to the equatorial plane 90o Molecular Geometry Linear (AB2) Trigonal Planar (AB3) Bent (AB2E) Tetrahedral (AB4) Trigonal Pyramidal (AB3E) Bent (AB2E2) Trigonal Bipyramidal (AB5) Distorted Tetrahedron or “seesaw” (AB4E) T-shaped (AB3E2) Linear (AB2E3) Octahedral (AB6) Square Pyramidal (AB5E) Square Planar (AB4E2) Applying VSEPR theory - (1) Lewis structure, (2) count electron clouds around central atom, (3) determine appropriate VSEPR electron cloud geometry first, (4) then determine molecular geometry based on the position of atoms in space Remember: Multiple bonds count as one cloud in VSEPR theory Molecular geometries of more complicated molecules with more than one central atom (apply VSEPR theory to each central atom)