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Unformatted text preview: IMPORTANT TERMS AND CONCEPTS Questions and Problems ' 35 Atomic mass unit (amu) Electronegative Periodic table Atomic number Electropositivc Polar molecule Atomic weight Ground state Primary bonding Bohr atomic model Hydrogen bond Quantum mechanics Bonding energy Ionic bond Quantum number Coulombic force Isotope Secondary bonding Covalent bond Metallic bond Valence electron Dipole (electric) Mole van der Waals bond Electron configuration Pauli exclusion principle Wave~mechanical model Electron state REFERENCES Most of the material in this chapter is covered in college-level chemistry textbooks. Two are listed here as references. Brady. J. E... and E Senese, Chemistry: Matter and its Changes, 4th edition, John Wiley & Sons. Inc., Hobolten, NJ, 2004. QUESTIONS AND PROBLEMS Ebbing, D. D., S. D. Gammon. and R. 0. Rags- dale. Essentials of General Chemistry. 2nd edition. Houghton Mitflin Company, Boston. 2006. Additional problems and questions for this chapter may be found on both Student and Instructor Companion Sites at ww.wiiey.com/coflege/caflister. 2.1 Silicon has three naturally occurring isotopes: 92.23% of 2{‘Si, with an atomic weight of 27.9769 amu, 4.63% of 29Si, with an atomic weight of 28.9765 amu, and 3.09% of 308i. with an atomic weight of 29.9738 amu. On the basis of these data. confirm that the average atomic weight of Si is 28.0854 amu. 2.2 (a) How many grams are there in one anau of a material? (In) Mole. in the context of this book. is taken in units of gram-mole. On this basis, how many atoms are there in a pound—mole of a substance? 2.3 Allowed values for the quantum numbers of electrons are as follows: n:1,2.3.... i=0.1,2,3,....fl—1 m;=0.:|:].:i:2.:l:3.....-_tl sugar-lg The relationships between :1 and the shell des- ignations are noted in Table 2.1. Relative to the subshells. l = 0 corresponds to an s subshell ! = 1 corresponds to a p subshell I = 2 corresponds to a d subshell I = 3 corresponds to an f subshell For the K shell. the four quantum numbers for each of the two electrons in the is state, in the order of nim;m,. are 100%) and 100(—‘§). Note: In each chapter, most of the terms listed in the "Important Terms and Concepts“ section are defined in the Glossary. which follows Appendix E. The others are important enough to warrant treatment in a full section of the text and can be referenced from the table of contents or the index. 36 I Chapter 2 I Atomic Structure and lntoratnmie Banding Write the four quantum numbers for all of the electrons in the L and M shells, and note which correspond to the s. p, and d subshells. 2.4 Give the electron configurations for the fol- lowing ions: P54: P31 and Ni“. The Periodic Table 2.5 To what group in the periodic table would an element with atomic number 112 belong? 2.6 Without consulting Figure 2.6 or Table 2.2. de- termine whether each of the electron configu- rations given below is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices. (a) ISZZYZZpSBSzSpS (b) 1522.922p63sz3p63dm4s‘24p6 (c) 1522522p63323p63d1°4524p64d5552 2.7 (a) What electron subshell is being filled for the rare earth series of elements on the periodic table? (11] What electron subshell is being filled for the actinide series? Bonding Forces and Energies 2.8 Calculate the force of attraction between a Ca2+ and an 02‘ ion the centers of which are separated by a distance of 1.25 nm. 2.9 The net potential energy between two adja- cent iOns, E N, may be represented by the sum of Equations 2.8 and 2.9; that is, (2.11) Calculate the bonding energy E0 in terms of the parameters A, B, and :1 using the follow- ing procedure: 1. Differentiate EN with respect to r, and then set the resulting expression equal to zero, since the curve of EN versus :- is a minimum -at E0. 2. Solve for r in terms of A, B, and n, which yields re, the equilibrium interionic spacing 3. Determine the expression for Eu by substi- tution of r0 into Equation 2.11. 2.10 Consider a hypothetical X+—Y’ ion pair for which the equilibrium interionic spacing and bonding energy values are 0.38 nm and —S.3'}l eV. respectively. If it is known that n in Equa- tion 2.11 has a value of 8, using the results of Problem 2.9, determine explicit expressions for attractive and repulsive energies, E, and ER of Equations 2.8 and 2.9. Primary inter-atomic Bond: 2.11 (11) Briefly cite the main differences between ionic, covalent, and metallic bonding. (b) State the Pauli exclusion principle. 2.12 Compute the percentage ionic character of the interatomic bond for each of the following compounds: MgO and 018. 2.13 Using Table 2.2, determine the number of co- valent bonds that are possible for atoms of the following elements: silicon, nitrogen, and neon. 2.14 What type(s) of bonding would be expected for each of the following materials: solid xenon, bronze, and rubber? Secondary Bonding or van der Waals Bonding 2.15 Explain why hydrogen fluoride (HF) has a higher boiling temperature than hydrogen chloride (HCI) (19.4 vs. —85° C), even though HF has a lower molecular weight. ...
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