Molecular Geometry Practice Test

Chemistry I-Honors Molecular Geometry Practice Test Solution Set

1. B The fact that the BeF2 molecule exists even though the electron configuration of beryllium is 1s2 2s2 implies that the Be-F bonds involve: A) resonance; B) sp hybrids; C) sp2 hybrids; D) sp3d hybrids; E) sp3; F) dative bonding (also called coordinate covalent bonding)

2. E The octahedral shape of the sulfur hexafluoride molecule, SF6 , is best explained by: A) hydrogen bonding B) sp3 hybridization C) resonance D) co-ordinate covalent bonding E) sp3d2 hybridization.

3. B What type of hybridization does tellurium show in the compound, TeBr4? A) sp3d2; B) sp3d; C) sp3; D) sp2; E) sp

4. F What is the bond angle between atoms in a molecule that exhibits the bent, or V-shape, as in water? A) 75; B) 109.5; C) 90; D) 120; E) 120 and 90; F) less than 109.5

5. E Which of the following molecules has three lone pairs and two bonding pairs of electrons?

A) CH3Cl; B) H2O; C) SeF3 (-1) ion; D) NF3; E) IBr2 (-1) ion.

6. B The triple bond in ethyne - C2H2 - is formed by what type of overlap of the p orbitals of the carbon atoms? A) sigma; B) pi; C) alpha; D) mu; E) omega.

7. D Which of the following geometric structures does not exhibit uniform bond angles? A) trigonal pyramid; B) tetrahedral; C) square planar; D) trigonal bipyramid; E) octahedral.

8. F What term is used to describe a hydrocarbon (a compound containing only hydrogen and carbon atoms) if it contains only single bonds between carbon atoms (as well as between the carbons and hydrogens)? A) resonance; B) unsaturated; C) planar; D) fatty acids; E) biplanar; F) saturated

+1 9. E What is the molecular shape of the ammonium ion - NH4 ? A) bent; B) trigonal planar; C) trigonal pyramid; D) trigonal bipyramid; E) tetrahedral.

-2 10. C What is the hybridization exhibited by sulfur in the sulfite ion (SO3 )? A) sp; B) sp2; C) sp3; D) sp3d; E) sp3d2.

11. B If a single pi bond exists between the atoms of C and O in CO2, what type of bond exists? A) single; B) double; C) triple; D) resonant; E) van der Waals; F) dative.

12. +1 What is the formal charge on sulfur in the sulfur dioxide molecule?

13. sp2 What type of hybridization is exhibited by either of the carbon atoms in the ethene molecule?

The formula for ethene is C2H4. -2-

For the next set of questions, use the following key to identify the shape of the molecule:

A) jigsaw; B) bent (or V-shaped); C) trigonal pyramid; D) octahedral; E) T-shaped; F) trigonal planar; G) tetrahedral; H) square-based pyramid; I) square planar; J) hexagonal ; K) trigonal bipyramid; L) seesaw (or teeter totter); M) linear

Be sure to make the letter clearly legible - if I can't read it, it will be marked wrong!

2- -1 14. F carbonate ion CO3 21. G perchlorate ion (-1) ClO4

24 e-1 = 3 / 0 (# bonded e-1 / # lone pair e-1) 32 e-1 = 4 / 0

-1 15. M carbon dioxide CO2 22. M triiodide ion (-1) I3

16 e-1 = 2 / 0 22 e-1 = 2 / 3

16. D sulfur hexafluoride SF6 23. I xenon tetrafluoride XeF4

48 e-1 = 6 / 0 36 e-1 = 4 / 2

-2 17. C phosphine PH3 24. E arsenic trichloride ion (-2) AsCl3

8 e-1 = 3 / 0 28 e-1 = 3 / 2

-2 18. B hydrogen telluride H2Te 25. F germanium trioxide ion (-2) GeO3

8 e-1 = 3 / 0 24 e-1 = 3 / 0

19. H iodine pentachloride ICl5 26. K antimony (V) chloride SbCl5

42 e-1 = 5 / 1 40 e-1 = 5 / 0

3- 20. L tellurium tetrachloride TeCl4 27. G phosphate ion PO4

34 e-1 = 4 / 1 32 e-1 = 4 / 0 -3-

28. A Which of the following structural formulas shows a cis geometric isomeric form?

C) H2C H D) H Cl \ / | | C=C H---C---C---H / \ | |

H CH2 Cl H

E) both A and C; F) both C and D.

Consider the pentane molecule for the next set of questions.

29. . C5H12 What is the molecular formula for this compound?

30. There are three isomers of this compound - not counting any cyclic forms. Draw the skeletal model for these three isomers (do not draw any cyclic forms).

C | C--C--C--C--C C--C--C--C C--C--C | | C C

31. none How many pi bonds are contained within this compound?

32. How does the bond angle in the CO2 molecule differ from than in the SO2 molecule? Why aren't they the same? Which is greater? Show by giving the bond angles and/or drawing the structures.

o o Bond angle of CO2 (180 ) > Bond angle of SO2 (<120 )

The carbon dioxide molecule does not have any lone pair electrons distorting the shape. The sulfur dioxide molecule shows resonance (which doesn’t affect the shape), but it does have a single lone pair that distorts the shape. The shape is based on the sp2 hybridization or the trigonal planar shape with a normal bond angle of 120o.