Exam 3A KEY

Exam 3A KEY - tramw—(please print as name appears on UNC roll 1A(4 pts Write the full electron configuration for Pb Z=82(do NOT use noble gas

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: tramw— (please print as name appears on UNC roll) 1A. (4 pts) Write the full electron configuration for Pb, Z=82 (do NOT use noble gas shorthand). l‘sZZszzbasta “452501‘2‘65240W6 ‘(oszéi Hal/W" B. (4 pts) What is the predicted stable form of its ion? A) +1 ' B) +2 ' C) -—4_ BOV ' D) +4 E) +14 Explain your answer using electron configurations. [90M haw [Av] av [86 ' 2A. (6 pts) Which species is larger (circle one I) or K+ firm k+ “H B. Which concept explains the size differ : E’. A) p electrons are slightly higher in : ergy than s electrons in the same shell. B) Nuclear charge. C) Repulsion when two electron -. occupy the same orbital. D) A screening effect by the in I er electrons. 3. (4 pts) Give a set of four qu turn numbers for the highest energy electron in calcium. 4: n: 4 I: {’1 - ml: 9 ms=+’/z- OV'IZ— 4A. (2 pts) How m .- ny unpaired electrons are in the ground state Mo atom (2:42)? ‘ m Wag (ml...) B. (4 u 5) Write the electron configuration for Mo+ using noble gas shorthand. cm 415’ £12515 f 6" Name iflA (please print as name appears on UNC roll) ’euo‘hz 5 + éblock 5. (2 pts) The periodic table of known elements consists of s, p, d, and f blocks. If an of elements existed, how many elements across would this block be? 22+ l=# Olbotals =11 Orbduig - a X 2 e‘/ov~launl =22 damth 6. '(6 pts) For the ground state of platinum, Pt (2:78): A) how many electrons have m3 = +112? a la b (o B) how many electrons occupy p orbitals? 2P C) how many electrons occupy atomic orbitals with n=4? LleMpdeLtP‘l 7. (4 pts) Which of the following orbital designations islare acceptable for the electron in a hydrogen atom? -————-—- 15 5f 7d 93 [if 69L hsb’ £1:th is 6t: ’14 Q5 lo 8. (5 pts) An oxygen atom has the following electron configuration: 1s2 252 2px2 szz. Is this a ground state or an excited state atom? Explain. Exam state has t’ pamd (M Zpe .0 297 Wold amp . 2 I (brow/Id 810% a 224229: 29" 2P2 mum to] alga/mi? g 14 +H’ 9. (4 pts) For an atom of silicon, what is the effective nuclear charge felt by: A) the valence electrons +fl 2” Com = Z —- {O B) the n=2 electrons ‘HZ Z "“ 28 ’ 4 4‘ 4‘ j"? q‘ '7' __i<_E_:_____ k at F LS e 1': P I‘gr"::lrr:aeise print as na\rr/1e afiars on UNC roll) 3 10A. (6 pts) Which atom has a greater first ionization energy (circle one) or Se B. Which concept accounts for this difference: A) p electrons are slightly higher in energy than s electrons in the same shell. B) Repulsion when two electrons occupy the same orbital. ' C) A screening effect by the inner electrons. D) Zetf- 11. (4 pts) Rank the following atoms in order of increasing size: Al, Si. Ga, Ge. A4 Si, .. 31? AU ee< GO.) Gm 62¢. 12. (6 pts) From the list of elements {Se, 0, i, P, B] choose two elements that, when combined: A) form the most polar covalent bond: B “O F. B) form the longest single bond: & -- _L 0) form a compound of formula XYZ: & i J.- 50 —-, 0 13A. (6 pts) Rank the following species in order of increasrng bond length: NO" No+ 0F" 60 1’ \L “0“<~0“<0F“ cit-50:71: B. (4 pts) What is the formal charge on each atom in NO'? : "' Pam) = 6-2—4: -1 Eggéj — l31(0): 6—2—4; = g5 Name I "' E (please print as name appears on UNC roll) 14. (4 pts each) Draw a single valid Lewis structure for each of the following; draw a box around your final answer: A) HN03 B) OFz . .C) IF3 |+6+ig=24r (Mil-H206“ 7+Zl=%e" NéO‘I - db__ i ail." . - 2E: 15. (8 pts) Estimate the heat of reaction for following reaction: N2 + 3 0'2 —) 2 NCI3 Bond Bond enthalpy , -* v .. kJ/mol :NaNz -.Cl—-C‘J= N Im- .. ~ “ / \.. Im- Ci l Cl nat- ' :C\= Aw 29mm» » ipfivwmol) g 9mm) + 239mm!) —- loD(N’C|) AHVHQI ltd = 1341+ gem—“(4200 K) = 4AM l4) Name I " A (please print as name appears on UNC roll) 16. (4 pts) Rank the following ionic compounds in order of increasing lattice energy: ' MgO CaS NaCl Csl CsI< NaCl < CaS< MO 17. (8 pts) The diagram below is the Born-Huber cycle for the formation of crystalline potassium fluoride. mg) 4» 112F2®+2 Ktsge mask K _ Wits) Which step (e.g.,- #1), as labeled in the diagram, has an energy change with the same magnitude as the following process: ' A) the electron affinity of fluorine? B) one~half the bond enthalpy of molecular fluorine? C) the lattice energy of potassium fluoride? D) the heat of formation of potassium flouride? thigh ...
View Full Document

This note was uploaded on 04/05/2012 for the course CHEM 101 taught by Professor Farahh during the Spring '02 term at UNC.

Page1 / 5

Exam 3A KEY - tramw—(please print as name appears on UNC roll 1A(4 pts Write the full electron configuration for Pb Z=82(do NOT use noble gas

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online