Chapter 8 Test Study Guide Name: AP Chemistry 6 points DUE AT TEST (Wed., 12/13/17) Date: Topics to be covered on the December 13, 2017 test: bond bond energy ionic bond covalent bond polar covalent bond electronegativity (no table provided) ä bond polarity polar/dipolar/dipole moment ionic radius ionic radius trend ion (prediction of charge) cation anion isoelectronic Lewis structures duet rule octet rule (and exceptions to it) bonding pair shared pair lone pair (unshared pair) single bond double bond triple bond endothermic exothermic breaking bonds making bonds resonance delocalization VSEPR VSEPR shapes formal charge calculation of enthalpy of reaction using bond energy tables lattice energy 1) Explain the following variations in radius: (a) I - > I > I + (all have the same p + ; I + lost an e -, so p + attract electrons more and make radius smaller) (b) Ca 2+ > Mg 2+ > Be 2+ (same group; Ca 2+ has more energy levels, so valence electrons are farther from nucleus) (c) Fe > Fe 2+ > Fe 3+ (Fe 3+ has lost more electrons, so there s less repulsion and radius is smaller) 2) Place F, Br, and Br - in order of decreasing size. (Br - Br F) 3) (a) What is an isoelectronic series? (sequence of ions with the same number of e - ) (b) Which neutral atom is isoelectronic with each of the following ions? Ga 3+ (Ni) Zr 4+ (Kr) Mn 7+ (Ar) I - (Xe) Pb 2+ (Hg) 4) Identify at least two ions that have the following ground-state electron configurations: (a) [Ar] (P 3-, S 2-, Cl -, K +, Ca 2+ ) (b) [Ar]3d 5 (Fe 3+, Mn 2+ ) (c) [Kr] 5s 2 4d 10 (Sn 2+, In + ) 5) Consider S, Cl, K, and their most common ions. (a) List the atoms in terms of increasing size. (Cl S K) (b) List the ions in order of increasing size. (K + Cl - S 2- ) (c) Explain any differences in the orders of the atomic and ionic sizes. K = more energy levels, so larger than Cl or S K +, S 2-, Cl - are isoelectronic; S 2- has gained the most e -, so it is the largest because there is more electron replusion 6) For each of the following sets of atoms and ions, arrange the members in order of increasing size: (a) Se 2-, Te 2-, Se (Se < Se 2- < Te 2- ) (b) Co 3+, Fe 2+, Fe 3+ (Fe 3+ < Fe 2+ and Co 3+ < Fe 3+ )
[I WILL NOT ASK ONE THIS DIFFICULT] (c) Ca, Ti 4+, Sc 3+ (Ti 4+ < Sc 3+ < Ca) (d) Be 2+, Na +, Ne (Be 2+ < Na + < Ne) 7) Does the lattice energy of an ionic solid increase or decrease (a) as the charges on the ions increase? (increase) (b) as the sizes of the ions increase? (decrease) (c) Arrange the following substances according to their expected lattice energies (from lowest lattice energy to highest): MgS, KI, GaN, LiBr (KI, LiBr, MgS, GaN) 8) Explain the following trends in lattice energy: (a) NaCl > RbBr > CsBr (NaCl = smallest ions) (b) BaO > KF (BaO = higher charges than KF) (c) SrO > SrCl 2 (SrO = higher charges than Sr 2+ and Cl - ) 9) Using only a periodic table, select the most electronegative atom in each of the following sets (then check yourself with a table): a) Na, Mg, K, Ca b) Be, B, C, Si c) P, S, As, Se d) Zn, Ge, Ga, As 10) Arrange the following sets of bonds in order of increasing polarity: a) C F, O F, Be F b) O Cl, S Br, C P (O F, C F, Be F) (S Br, C P, O Cl) c) S C, B F, N O (S C, N O, B F) 11) Rank the following bonds in order of INCREASING ionic character (from most covalent to most ionic): N O, Ca O, C F, Br Br, K F (Br Br, N O, C F, Ca O, K F) 12) Draw the Lewis structures for each of the following. Then predict the bond angles and VSEPR shape: a) HF g) N 2 l) NH 3 r) CH 4 linear 180 linear 180 trigonal pyramid tetrahedral
b) CF 4 h) NO + m) HCN (central atom is carbon) (tetrahedral like [:N O:] + H-C N: methane) linear 180 linear 180 c) PH 3 i) CHCl 3 n) NH 4 + s) O 2 trigonal pyramid 107 tetrahedral 109.5 tetrahedral 109.5 linear 180 d) H 2 CO (central atom is carbon) o) SeF 2 t) HBr trigonal planar 120 bent 104.5 linear 180 e) POCl 3 j) SO 4 2- p) XeO 4 u) ClO 4 - tetrahedral tetrahedral tetrahedral tetrahedral f) PO 4 3- k) SO 3 2- q) ClO 2 - r) PCl 5 tetrahedral trigonal pyramid bent trigonal bipyramidal s) SeCl 6 t) ICl 5 u) TeF 4 v) PCl 3 octahedral square pyramid see-saw trigonal pyramid 13) Write the electron configurations for a) the cations Sr 2+, Cs +, Pb 2+, and In + [Kr] [Xe] [Xe]6s 2 5d 10 [Kr]5s 2 4d 10 b) the anions P 3-, Br -, and S 2- [Ar] [Kr] [Ar]
14) Which of the following ions have noble gas electron configurations? a) Fe 2+, Fe 3+, Sc 3+, Co 3+ b) Tl +, Te 2-, Cr 3+ c) Pu 4+, Ce 4+, Ti 4+ d) Ba 2+, Pt 2+, Mn 2+ 15) Which noble gas has the same electron configuration as each of the ions in the following compounds? a) cesium sulfide b) strontium fluoride [Xe] [Ar] [Kr] [Ne] c) calcium nitride d) aluminum bromide [Ar] [Ne] [Ne] [Kr] 16) For each of the following groups, place the atoms and ions in order of DECREASING size: a) Cu, Cu +, Cu 2+ b) Ni 2+, Pd 2+, Pt 2+ (Cu > Cu + > Cu 2+ ) (Pt 2+ > Pd 2+ > Ni 2+ ) c) O, O -, O 2- d) La 3+, Eu 3+, Gd 3+, Yb 3+ (O 2- > O - > O) (La 3+ > Eu 3+ > Gd 3+ > Yb 3+ ) e) Te 2-, I -, Cs +, Ba 2+, La 3+ (Te 2- > I - > Ba 2+ > La 3+ ) 17) Predict the empirical formulas of the ionic compounds formed from the following pairs of elements. a) Al and F b) K and S c) Y and O d) Mg and N AlF 3 K 2 S YO or Y 2 O 3 Mg 3 N 2 d) Ba and F e) Cs and Cl f) Li and N g) Al and O BaF 2 CsCl Li 3 N Al 2 O 3 18) Use the bond energy tables to estimate ÄH for each of the following reactions in the gas phase: (a) H 2 S + 3 F 2 > SF 4 + 2 HF [-1282 kj] (b) C 2 H 2 + 5/2 O 2 > 2 CO 2 + H 2 O [-1228 kj] 19) Use the bond energy tables to predict ÄH for the isomerization of methyl isocyanide to acetonitrile: CH 3 N C (g) > CH 3 C N (g) [-42 kj] 20) Use bond energies to predict ÄH for the combustion of ethyl alcohol. [-1276 kj] CH 3 CH 2 OH + 3 O 2 > 2 CO 2 + 3 H 2 O (first draw structures, then break and make bonds!) 21) Use bond energies to estimate ÄH for the following reaction: H 2 O 2 (aq) + CH 3 OH (aq) -----> H 2 CO (aq) + 2 H 2 O ( ) [-295 kj]
22) (a) What is the trend in electronegativity going from left to right in a row on the periodic table? (increases) (b) How do electronegativity values generally vary going down a column on the periodic table? (decrease) (c) How do the periodic trends of first ionization energy and atomic radius relate to electronegativity? (FIE follows EN trend, atomic radius is opposite EN trend) 23) What is the difference between an ionic bond and a polar covalent bond? (ionic = transfer of electron, most polar; polar covalent = unequal sharing of e - ) 24) Which has the largest dipole moment, an ionic bond, a covalent bond, or a polar covalent bond? (ionic) 25) p. 398 # 119 (see book for answer) 26) p. 397 #101 (see book for answer) 27) p. 397 #92 (resonance) 28) p. 393 #25 (see book for answer) 29) p. 393 #26 c = true; A = XeCl 2 is linear; B = SO 2 angle is larger than SCl 2 but smaller than CS 2 ; D = MINIMIZE repulsions! 30) p. 395 #61 (see book for answer) 31) p. 402-A 1) C 2) D 3) A 4) B 8) D 11) A 12) A 13) B