CHEM 1411 Sample Exam 3A - HCC Learning Web

CHEM 1411

Sample Exam 3A

Electron Configuration

2

CHEM 1411 Sample Exam # 3A Name:______________________________

Score:

Directions- please answer the following multiple-choice questions next to each number. Please show all your

work for bonus question and part(2) questions in the space provided.

Part (1) - Multiple Choice - (3 points each)

____ 1. Which atomic orbital is spherical in shape? (Note: you should know and be able to recognize the shapes

of the s orbital, px, py, and pz orbitals, and dxy, dyz, dxz, dx2-y2 and dz2 orbitals.)

(a) 2s (b) 3p (c) 3d (d) 4f (e) they are all spherical

____2. The maximum number of electrons that can be accommodated in a sublevel for which l = 3 is:

(a) 2 (b) 10 (c) 6 (d) 14 (e) 8

____3. Which of the following electron configurations is correct for nickel?

(a) [Ar] 4s1 3d

8 (b) [Kr] 4s

1 4d

8 (c) [Kr] 4s

1 3d

8 (d) [Kr] 4s

2 3d

8 (e) [Ar] 4s

2 3d

8

____4. Which one of the following sets of quantum numbers could be those of the distinguishing (last) electron

of P?

(a) n = 4, l = 0, ml = 0, ms = +1/2 (b) n = 3, l = 1, ml = 9, ms = -1/2

(c) n = 3, l = 1, ml = +1, ms = +1/2 (d) n = 5, l = 2, ml = +2, ms = -1/2

(e) n = 4, l = 2, ml = -1, ms = +1/2

____5. Select the term best describing the series of elements: Mn, Fe, Co, Ni, Cu.

(a) d-transition metals (b) representative elements (c) metalloids

(d) alkaline earth metals (e) halogens

____6. This of the following terms accurately describes the energy associated with the process:

Li(g) Li+(g) + e

-

(a) electron affinity (b) binding energy (c) ionization energy

(d) electronegativity (e) none of these

____7. Which of the following is the most basic oxide?

(a) N2O3 (b) N2O5 (c) P4O6 (d) P4O10 (e) Bi2O5

____8. Which statement is wrong?

(a) The atomic weight of carbon is about 12.

(b) The most stable ion of lithium is Li+.

(c) A phosphorus atom is larger than an antimony atom.

(d) The radius of a sodium atom is larger than that of a sodium cation.

(e) Oxygen has a less negative electron affinity than fluorine.

____9. Which of the following pairs of elements and valence electrons is incorrect?

(a) Al - 3 (b) Br - 7 (c) S - 4 (d) Sr - 2 (e) Tl - 3

____10. Which of the following does not have a noble gas electron configuration? (or Which of the following

is not isoelectronic with a noble gas?)

(a) S2-

(b) Ba+ (c) Al

3+ (d) Sb

3- (e) Sc

3+

3

____11. The valence electrons of representative elements are

(a) in s orbitals only.

(b) located in the outermost occupied major energy level.

(c) located closest to the nucleus.

(d) located in d orbitals.

(e) located in the innermost occupied shell.

____12. Which one of the compounds below is most likely to be ionic?

(a) GaAs (b) ScCl3 (c) NO2 (d) CCl4 (e) ClO2

____13. What is the total number of electrons in the correct Lewis dot formula of the nitrate ion?

(a) 8 (b) 24 (c) 26 (d) 30 (e) 32

____14. Choose the molecule that is incorrectly matched with the electronic geometry about the central atom.

(a) CF4 - tetrahedral (b) BeBr2 - linear (c) H2O - tetrahedral

(d) NH3 - tetrahedral (e) PF3 - pyramidal

____15. Which molecule has a linear arrangement of all component atoms?

(a) CH4 (b) H2O (c) CO2 (d) NH3 (e) BF3

____16. A neutral molecule having the general formula AX3 has two unshared pair of electrons on A.

What is the hybridization of A?

(a) sp (b) sp2 (c) sp

3 (d) sp

3d (e) sp

3d

2

____17. Which molecule is nonpolar?

(a) H2Se (b) BeH2 (c) PF3 (d) CHCl3 (e) SO2

____18. Which response contains all of the characteristics listed that should apply to phosphorus trichloride,

PCl3, and no other characteristics?

(1) trigonal planar

(2) one unshared pair of electrons on P

(3) sp2 hybridized at P

(4) polar molecule

(5) polar bonds

(a) 1, 4, 5 (b) 2, 3, 4 (c) 1, 2, 4 (d) 2, 4, 5 (e) another combination

____19. Carbon monoxide has ten bonding electrons and four anti-bonding electrons. Therefore it has a bond

Order of _____.

(a) 3 (b) 7 (c) 1 (d) 5/2 (e) 2

____20. What is the correct electron configuration for the molecular ion, B2+?

(a) 1s2 *1s

2 2s

2 *2s

2 2p

2 (b) 1s

2 *1s

2 2s

2 *2s

2 2py

2

(c) 1s2 *1s

2 2s

2 *2s

2 2py

2 2pz

1 (d) 1s

2 *1s

2 2s

2 *2s

2 2p

1 2py

1

(e) none of the above.

4

Part (2) - Show all your work. ( 8 points each)

21. What is the frequency and energy of light having a wavelength of 958 nm?

(c = 3.00x108 m/s , h = 6.63 x10

-34 J.s)

22. Calculate the enthalpy change, H , for the following gas- phase reaction using bond energy data.

Dissociation energy

H H H H H-Cl 435KJ/mol

\ C-H 413 KJ/mol

C=C + H-Cl H - C - C - H C-C 348 KJ/mol

\ C=C 614 KJ/mol

H H H Cl C-Cl 328 KJ/mol

23. For SO3 2 -

, sulfate ion, draw the Lewis structure (by counting valence electrons of each atom),

determine the electron-domain geometry, molecular geometry, hybridization, and show the angle

between the bonds in a drawing. S is the central atom, all other

atoms are attached to S.

5

24. Given N2 2-

, using molecular orbital and valence bond theory;

a) Write molecular orbital configuration

b) Determine BOND ORDER and indicate stability

c) Identify the MAGNETIC properties (paramagnetic or diamagnetic)

25. Calculate the energy and wavelength of the radiation released when an electron in a hydrogen atom moves

from n =5 to n = 2. (RH = 2.18x10-18

J, c = 3.00x108 m/s , h = 6.63 x10

-34 J.s)

BONUS Question- Show all your work.(10 points)

The transition of an electron from n =5 to a lower energy level releases energy with a wavelength of 434 nm.

Calculate the final transition level of this electron..

6

CHEM 1411 EXAM # 3A (KEY) 1) A 2) D 3) E

4) C 1s2 2s

2 2p

6 3s

2 3p

3

5) A 6) C 7) E 8) C 9) C 10) B 11) B 12) B 13) B 14) E

15) C 16) B 17) B 18) D 19) A 20) E


21. Frequency ν = (c/λ ) = (3.00x108 m/s)/ (958x10

-9 m) = 3.13 x10

14 s

-1

Energy ΔE = h ν = (6.63 x10-34

J.s )( 3.13 x1014

s-1

) = 2.08 x10-19

J

22. H = [ 614 + 435 ] - [ 328 + 348 + 413 ] = - 40 KJ

23. In this example, SO32-

, the Lewis diagram shows sulfur at the center with one lone electron pair. The sulfur

and and one oxygen are bonded through a double bond which counts as "one electron pair". Hence the

molecule has four electron pairs and is tetrahedral.

SO3 2-

= 6e- + 3 (6e

-) + 2e

- = 26e

- = 13 p.e

-

a) tetrahedral b) triagonal pyramidal c) sp

3 d) 107

o

24. N2 2-

= 16e- = ( 1s )

2 ( 1s

* )

2 ( 2s )

2 ( 2s

* )

2 ( 2py )

2 ( 2pz )

2 ( 2px )

2 ( 2py

* )

1( 2pz

* )

1

Has unpaired electrons paramagnetic

25. ΔE = (-2.18x10-18

J)(1/nf2 -1/ni

2) = (-2.18x10

-18J)(1/2

2 -1/5

2) = (-2.18x10

-18J)(1/4 -1/25)

= (-2.18x10-18

J)(0.25 - 0.04) = (-2.18x10-18

J)(0.21) ΔE = -4.59x10-19

J

λ = (hc/ ΔE) = (6.63x10-34

J.s)(3.00x108m)/(2.59x10

-19 J) = 4.35x10

-7 m

BONUS

ΔE = (hc/ λ) = 6.63x10-34

J.s)(3.00x108m) / (434x10

-9 m) = 4.58x10

-19 J

ΔE = (-2.18x10-18

J)(1/nf2 -1/ni

2) (-4.58x10

-19 J) = (-2.18x10

-18J)(1/nf

2 -1/5

2)

(-4.58x10-19

J) = (-2.18x10-18

J)(1/nf2 - 0.04) (-4.58x10

-19 J) / (-2.18x10

-18J) = (1/nf

2 ) - 0.04

0.21 = 1/nf2 - 0.25 0.21 + 0.04 = 1/nf

2 0.25 = 1/nf

2 nf

2 = 1/0.25 = 4 nf = 2

7

CHEM 1411

Sample Exam 3B

8

CHEM 1411 Sample Exam # 3B Name:______________________________

Score:


work for bonus question and part (2) questions in the space provided.


____ 1. An atom has a valence shell electron configuration of ns1. To which group of elements in the periodic

table does it belong?

A. transition metals B. alkaline earth metals C. rare earth metals

D. alkali metals E. halogens

____2. The maximum number of electrons that can be accommodated in a sublevel for which l = 2 is:

A. 2 B. 10 C. 6 (d) 14 (e) 8

____3. Write the electron configuration for the chromium (III) ion, Cr3+

, using the appropriate noble-gas inner

core for abbreviation.

A. [Ar]4s23d

5 B. [Ar]4s

14d

2 C. [Ar] 3d

3 D. [Kr]3d

4 E. [Ar]4s

13d

5

____4. Which set of quantum numbers is correct and consistent with n = 4?

A. l = 3, ml = –3, s = +1/2 B. l = 4, ml = +2, s = – 1/2 C. l = 2 , ml = +3 , s = +1/2

D. l = 3, ml = –3 , s = +1 E. l = 4, ml = +4, s = –1/2

____5. Select the term best describing the series of elements: Cl, F, Br, I.

A. d-transition metals B. representative elements C. metalloids

D. alkaline earth metals E. halogens

____6. The ground–state electronic configuration of the manganese (Mn) atom is________________.

A. 1s22s22p63s23p64s2 4d5 B. 1s22s22p63s23p63d7 C. 1s22s22p63s23p64s24p5

D. 1s22s22p63s23p6 4s23d5 E.1s22s22p63s23p64s24d5

____7. Which of the following oxides is/are basic? SO2, MgO, Li2O, N2O

A. MgO and N2O B. MgO and Li2O C. SO2 and N2O

D. MgO only E. all of these

____8. In moving down column IIA of the periodic table;

A. electron affinity increases B. ionization energy decreases

C. electronegativity increases D. the oxidation state (charge) remain constant

E. electropositivity remains constant

____9. Arrange the following atoms in order of increasing atomic radius: N,

K, As, Fr .

A. N < K < As < Fr B. N < As < K < Fr C. As < K < N < Fr

D. Fr < K < As < N E. K< Fr < As < N

9

____10. Which of the following has a bond order of 3?

I. N2 II. CN- III. O2 IV. Cl2

A. I and II B. I, II, and IV C. I and III D. I and IV E. only I

____11. Which of the following does not have a noble gas electron configuration? (or Which of the following

is not isoelectronic with a noble gas?)

A. S2-

B. Ba+2

C. Al2+

D. Mg2+

E. two of these

____12. Which of the following is correct about BF3 is correct?

A. tetrahedral, planar B. trigonal planar, nonpolar C. trigonal planar, polar

D. trigonal pyramidal, nonpolar E. tetrahedral, non-polar

____13. What is the electron-domain geometry of CO32-

?

A. trigonal bipyramidal B. linear C. trigonal planar

D. tetrahedral E. none of these

____14. Which of the following has electron geometry and molecular geometry the same/?

A. H2O B. NH3 C. O3 D. NF3 E. CH4

____15. What is the total number of valence electrons in PO43-

?

A. 23 e- B. 24 e

- C. 32 e

- D. 26 e

- E. 12 e

-

____16. What are the correct hybridization and approximate bond around nitrogen atom in NF3?

A. sp2, 120

0 B. sp

3, 109

0 C. sp

3, 107

0 D. sp, 180

0 E. sp, 120

0

____17. Which of the following molecule is a non-polar covalent?

A. CO2 B. CCl4 C. BF3 D. SO3 E. all of these

____18. Which of the following is not true?

A. The shape of carbon dioxide molecule is linear.

B. When a metal reacts with a nonmetal a covalent bond is formed.

C. A double bond occurs when two atoms share two pairs of electrons.

D. nonpolar covalent bond results from equal sharing of a pair of electrons between atoms

in a molecule

E. All are true

____19. What is the formal charge of N in :C N: ?

A. 0 B. 4 C. -1 D. 3 E. +1

____20. Which of the following is the correct electron configuration for C2?

A. 1s2 2s

2 2py

2 *1s

2 *2s

2 *2py

2 B. 1s

2 *1s

2 2s

2 *2s

2 2py

2 *2pz

1 2p

1

C. 1s2 *1s

2 2s

2 *2s

2 2py

2 2pz

2 D. 1s

2 *1s

2 2s

2 *2s

2 2py

1 2pz

1

E. 1s2 *1s

2 2s

2 *2s

2 2py

1 *2py

1 2pz

1 *2pz

1

10


21. Consider a yellow sodium light emission, which a frequency of 5.09x1014

Hz;

a) what is the wavelength in nm? b) calculate the energy of the yellow light.

(c = 3.00x10 8 m/s , h = 6.63x10

-34 J. sec , RH = 2.18x10

-18 J)

22. Calculate the enthalpy change, Δ H, for the following reaction using bond dissociation energy data.

H H H H

H C C H + Cl Cl H C C Cl + H Cl

H H H H

Bond energies in kJ/mol: C-C = 348; C-H = 414; Cl-Cl = 242; C-Cl = 327; H-Cl = 431

23. For NO3-, nitrate ion, draw the Lewis structure (by counting the valence electrons of each atom),

determine the electron-domain geometry, the molecular geometry, resonances structures,

hybridization, and show the angles between the bonds in a drawing. N is the central atoms, all other

atoms are attached to N.

11

24. Given O2 2-

, using molecular orbital and valence bond theory;

a) Write molecular orbital configuration

b) Determine BOND ORDER and indicate stability

c) Identify the MAGNETIC properties (paramagnetic or diamagnetic)

25. Write the core electron configurations for the followings and determine the total number of unpaired

electrons and magnetic properties (paramagnetic or diamagnetic) in each.

a) Chromium (Cr) _______________________________________ ,________, _________

b) Ferric Ion (Fe3+

) ____________________________________ ,________, ___________

BONUS Question- Show all your work.(10 points)

(RH = 2.18x10-18

J, c = 3.00x108 m/s , h = 6.63 x10

-34 J.s)

The wavelength of 410 nm results from a transition from an upper energy level to n=2. What is the principal

quantum number of the upper level?

12

CHEM 1411 EXAM # 3B (KEY)

Part (1)

1. D 2. B l= 2 P orbital 3 orbitals 6 electrons 3. C [Ar] 3d3

4. A 5. E 6. D 7. B 8. B 9. B 10. A 11. C 12. B

13. C 14. E 15. C 16. C 17. E 18. B 19. A 20. C

Part (2)

21. C = λν λ = C/ν = (3.00x108m/s)/ (5.09x10

14 s

-1) λ =5.89x10

-7 m x10

9 = 589 nm

Δ E = hν = (6.63x10-34

J.s)(5.09x1014

s-1

) Δ E = 3.38x10-19

J

22. Δ H = [ D(C-H) + D(Cl-Cl)] – [ C-Cl) + D (H-Cl)] = [ 414 + 242] – [327 + 431] Δ H = - 102 kJ

23. NO3 = 5e

+ 3(6e

) +1e

= 24 e

=12 pair electrons Three resonances are:

. . . .

:O: :O:

:O:

. . N . . N . . . . N

:O: :O: :O: :O: :O: :O:

electron geometry: trigonal planar molecular geometry: trigonal planar

angle: 120o

hybridization: sp2 Polarity: non-pola molecule

24. O22-

= 2(8) + 2 = 18 electrons

(σ1s)2 (σ1s*)

2 (σ2s)

2 (σ2s*)

2 (σ2px)

2 (π2py)

2(π2pz)

2(π2py*)

2(π2pz*)

2

Bond – Order = [(10) – (8)] / 2 = 2/2 = 1 single bond, diamagnetic

25. Cr : [Ar] 4s1 3d

5 6 unpaired electrons paramagnetic

Fe3+

: [Ar] 3d5

5 unpaired electrons paramagnetic

BONUS Question

Δ E = hc/λ = (6.63x10-34

J.s)(3.00x108 m)/ (410x10

-9 m) = 4.85x10

-19 J

Δ E = (-2.18x10-18

J) (1/nf2 – 1/ni

2) 4.85x10

-19 J = (-2.18x10

-18J) (1/2

2 – 1/ni

2)

(4.85x10-19

J)/ ((-2.18x10-18

J) = (1/22 – 1/ni

2)

- 0.223 = ( 0.25 – 1/ni2) 0.223 – 0.25 = - 1/ni

2 1/ni

2 = 0.0275 ni

2 = 36.36 ni = 6

13

CHEM 1411

Sample Exam 3C

Average Bond Energies (kJ/mol)

14

CHEM 1411 EXAM # 3C Name: _________________________

Dr. Pahlavan

Score:


work for bonus question and part (2) questions in the space provided.


_____ 1. In drawing Lewis dot structures, the dots represent_______________ .

A. protons B. valence electrons C. neutrons D. charges E. bonds

_____ 2. The proper Lewis structure (electron-dot structure) for N2 is:

A. (: N = N :) B. (:N::N::) C. (:N:::N:) D. (: N::N:) E. (::N::N:: )

_____ 3. What is the total number of valence electrons in PO43-

?

A. 12 e- B. 24 e

- C. 32 e

- D. 26 e

- E. 16 e

-

_____ 4. Which one has the largest radius ?

A. Te-2

B. Ba+2

C. Cu2+

D. Cu+ E. Ag

+

_____ 5. What is the formal charge of C in :C N: ?

A. 0 B. 4 C. -1 D. 3 E. +1

_____ 6. Which of the following elements has two pairs electrons in its Lewis dot Symbol?

A. C

B. S C. Cl D. N E. He

_____ 7. Which of the following is NOT an element of the fourth period in the periodic table?

A. Co B. K C. Mg D. Ca E. Kr

_____ 8. The general outer shell electron configuration for atoms of all Halogens is ____________ .

A. ns2np

6. B. ns

2np

5. C. ns

2np

4. D. ns

2np

3. E. ns

2np

1.

_____ 9. Which sets of quantum numbers are unacceptable?

A. n=3, l= -2, ml= 0, ms= +½ B. n=2, l= 2, ml= -1, ms= -½

C. n=6, l= 2, ml= -2, ms= +½ D. both A & B are unacceptable E. All acceptable

_____ 10. The ion whose outer shell electronic configuration is 2s2 2p

6 is:

A. Li + B. F

– C. S

2– D. Mg

2 + E. Two of these

15

_____ 11. Which of the following is the electron configuration for Cr+3

?

A. [Ar] 3d74s

2 B. [Ar] 4s

2 4d

7 C. [Ar] 4s

24d

1 D. [Ar]3d

3 E. [Ar]4s

13d

2

_____12. Which of the following statement is false?

A. The total number of electrons with n=4, l=1 is six.

B. The total number of orbitals in a shell with n=3 is three.

C. The allowed values of l for the shell with n=2 are two.

D. The subshell with n=3 and l=1 is designated as the 3d subshell.

E. All of these are correct

_____13. Choose the correct order of ionization energy of the atoms, S, Si, Ge?

A. S< Si < Ge B. Ge < Si < S C. Si < Ge < S D. Ge < S<Si E. Si < S < Ge

_____ 14. How much energy does a photon of light with a frequency of 4.60 x 1014

s-1 have?

(h = 6.626 x 10-34

J.s and c =3.00x108 m/s)

A. 3.05x10-19

J B. 1.44x10-19

J C. 1.44x10-48

J D. 3.05x1019

J E. None of these

_____ 15. How many equivalent resonance forms can be drawn for carbonate ion, CO32-

?

A. 1 B. 2 C. 3 D. 4 E. 0

_____ 16. Choose from the atoms listed below, the one with the highest electro-negativity.

A. Li B. Na C. S D. Be E. Mg

_____17. Which of the following atoms can accommodate an excess of 8 electrons in Lewis structures

where they are the central atom?

A. F B. O C. C D. N E. S

_____18. Which of the following molecule is exception to octet rule?

A. N2 B. CO2 C. BF3 D. SO2 E. O3

______19. What is the wavelength of light in nm, that has a frequency of 6.6 x 1014

Hz?

(h = 6.626 x 10-34

J.s and c =3.00x108 m/s )

A. 3.0x108 B. 4.55x10

-7 C. B. 4.55x10

9 D. 455 E. 4.55x10

7

______20. Which of the following ground-state electron configurations is possible (allowed)?

A. 1s22s

32p

3 B. 1s

22s

22p

33s

6 C. 1s

22s

22p

63s

23p

6

D. 1s22s

22p

63s

23p

64s

23d

4 E. two of these

16


21. Consider a photon of Red light with a wavelength of 690.nm? Calculate;

a) Frequency b) Energy (h=6.626 x 10-34

J.s , c=3.00 x 108m/s )

22. Estimate the enthalpy change (∆Hrxn) of reaction, HCN (g) + 2H2 (g) CH3NH2 (g), using provided

bond energies table.

23. Draw all the possible resonance structures for azide ion, N3 . Determine (circle) the most possible

correct Lewis dot structure.

24. Write the correct electron configuration and core configuration for the followings;

Br ______________________________________ , _________________________________

Cu+2

_____________________________________, _________________________________

25. Answer the following as true (T) or false(F)

__________ a. Na+, Al

3+, and Ne are isoelectrons.

___________b. NaCl is ionic compound and Cl2 is polar covalent.

___________c. PCl5 molecule disobey octet rule.

___________ d. Chromium, Cr, has core configuration [Ar] 4s1 3d

5.

17

Bonus Question - Show all your work. (10 points )

21. Consider the two resonance structures of CO2.

Structure A Structure B

a. Assign formal charges to both O and C in structure B.

b. Select the major structure (A or B) based on charge and electronegativity. Explain your

answer.

18

CHEM 1411 EXAM # 3C (KEY)

PART - 1

1. B 6. B 11. D 16. C

2. C 7. C 12. D 17. E

3. C 8. B 13. A 18. C

4. A 9. D 14. A 19. D

5. C 10. E 15. C 20. C

PART – 2

21. (a) ν = c/ λ = (3.00x108m/s) / 690x10

-9 m) = 4.35x10

14 s

-1

(b) E = h ν = (6.626x10-34 J.s)( 4.35x1014

s-1

) = 2.88x10-19

J

22. Hrxn = mDBonds Broken - nDBonds Broken

Hrxn = [D(C-H) + D(C triple N) + 2D(H-H) ] – [ 3D(C- H) + D(C-N) + 2D(N-H)]

= [ (413) + (891) + 2(436)] – [ 3(413) + 305 + 2(393))] = -54 kJ

23. N3 = 3(5) + 1 = 16 = 8 pe

-

24.

Br Electron Configuration 1s2 2s

2 2p

6 3s

2 3p

6 4s

2 3d

10 4p

5

Core Configuration [Ar] 4s2 3d

10 4p

5

Cu+2

Electron Configuration 1s2 2s

2 2p

6 3s

2 3p

6 3d

9

Core Configuration [Ar] 3d9

25. a. T b. F c. T d. T

BONUS

a. Structure B: Formal Charges O(-1), C(0), O (+1)

b. Structure A is the major structure based on formal charges. Formal charges on carbon and

both oxygens are zero.

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CHEM 1411 Sample Exam 3A - HCC Learning Web