Oxidizing power across row as Oxidizing power down column as Jespersen/Brady/Hyslop
Nonmetals Oxidizing power of nonmetal (how easily reduced) parallels . Reactivities of Elements Related to Electronegativities Metals Low , means easy to oxidize (groups I and IIA) High , means hard to oxidize (Pt, Ir, Rh, Au, Pd) Reactivity across row as Reactivities of Elements Related to Electronegativities Parallels between and its reactivity Tendency to undergo redox reactions Elements in different regions of Periodic Table i.e., metal and nonmetal Have different ’s Bonding predominantly ionic Jespersen/Brady/Hyslop Result Elements in same region of Periodic Table i.e., 2 nonmetals Have similar ’s Bonding more covalent 0.5 < < 1.7 polar covalent Jespersen/Brady/Hyslop < 0.5 Means almost purely covalent Nonpolar < 5% ionic Net in energy Hf° 1.7 means mostly ionic >50% ionic More electronegative element almost completely controls e Ionic Compounds Ionic crystals: Exist in 3-dimensional array of cations and anions = lattice structure Ionic chemical formulas: Always written as empirical formula Smallest whole number ratio of cation to anion Jespersen/Brady/HyslopĮnergetics Must look at energy of system to answer these questions For any stable compound to form from its elements Potential Energy of system must be lowered. Why does this occur? Why is e transferred? Why Na+ and not Na2+ or Na? Why Cl and not Cl2 or Cl+? Jespersen/Brady/Hyslop Ionic Bond Attraction between + and – ions in ionic compound. Ionic Compounds Formed from metal and nonmetal Na + Cl Formation of lattice stabilizes ions Jespersen/Brady/Hyslop Non-metals have Very exothermic electron affinities Metal - nonmetal bonds are ionic because: Metals have Low ionization energies Easily lose e– to be stable Ionic Bonds Result from attractive forces between oppositely charged particles Na+ Occurs in ionic solid e’s transferred from 1 atom to another Simpler We will look at this first Two Classes of Bonds Covalent bonding Occurs in molecules Sharing of e’s Why study? Changes in these bonding forces are the underlying basis of chemical reactivity During reaction: Break old bonds Form new bondsĬhemistry: The Molecular Nature of Matter, 6E Chapter 9: The Basics of Chemical BondingĬhemistry: The Molecular Nature of Matter, 6E Jespersen/Brady/HyslopĬhemical Bonds Attractive forces that hold atoms together in complex substances Molecules and ionic compounds