Chapter 14 periodic patterns

Chapter 14 periodic patterns - 14 14.1 14.2 Chapter a)...

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14 Chapter Periodic Patterns in the Main-Group Elements: Bonding, Structure, and Reactivity 14.1 a) Electron configuration, atomic size, ionization energy, and electronegativity. b) The principal quantum number n is related to the size and energy of the orbital. The azimuthal quantum number l gives the shape of the orbital. The superscript tells the number of electrons in the subshell. c) The value of n. d) In a group, n varies. Across a period, the number of electrons varies. e) The number of valence shell electrons is given by the "old" group number, or by the "new" group number minus ten. 14.2 a) Z eff increases across a period and decreases down a group. b) As you move to the right across a period, the atomic size decreases, the IE 1 increases and the EN increases, all as a result of the increased Z eff . 14.3 a) ICl is polar; Br 2 is non-polar. The electronegativity of Cl is greater than that of I, so the I end of ICl will be partially positively charged due to the greater "pull" of the Cl on the shared electrons. b) ICl will have a higher boiling point than Br 2 since dipole-dipole forces in ICl are greater than dispersion forces in Br 2 . 14.4 As an atom becomes smaller, its electrons are closer to the nucleus and are therefore more tightly held, therefore increasing the ionization energy. The two trends are opposite to one another. 14.5 In general, stronger bonds (higher bond energy) are also shorter and less reactive. (This assumes the same number and type of bonds.) 14.6 They are similar in that they involve sharing of electrons between atoms. They are different in that covalent bonding includes sharing between a small number (usually two) of atoms, while metallic bonding involves essentially all the atoms in a given sample. 14.7 The bonding would change from metallic to (perhaps) very polar covalent to ionic as the "other" element went farther to the right. The electronegativity, ionization energy, and electron affinity all change as you move to the right. The atomic properties of the leftmost element and the "other" element become increasingly different, causing the type of bonding to change in response. 14.8 A pair of atoms bonded only by a single bond use a σ bond, which is cylindrically symmetric; i.e., its energy will not change significantly with rotation. The "second" bond of the double bond is a π bond, which needs to be in a specific geometric orientation to form. Rotation of the molecule about this bond would break this π bond, a process that requires more energy than is available under ordinary circumstances. 14.9 The elements at the left (metals) form cations, which are smaller than the corresponding atoms; the elements at the right (nonmetals) form anions, which are larger than the corresponding atoms. 14.10
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This note was uploaded on 01/21/2010 for the course CHEM 1A taught by Professor Kobiashi during the Spring '07 term at Ventura College.

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Chapter 14 periodic patterns - 14 14.1 14.2 Chapter a)...

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