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Chapters 7, 8, & 9 Test Review

22. 1s22s22p63s23p3

Atoms of an element, X, have the electronic configuration shown above. The compound
most likely formed with magnesium, Mg, is

A) MgX C) MgX2 E) Mg3X2
B) Mg2X D) Mg2X3

40. The geometry of the SO3 molecule is best described as

A) trigonal planar C) square pyramidal E) tetrahedral
B) trigonal pyramidal D) bent

41. Which of the following molecules has the shortest bond length?

A) N2 C) Cl2 E) I2
B) O2 D) Br2

43. The elements in which of the following have most nearly the same atomic radius?

A) Be, B, C, N C) Mg, Ca, Sr, Ba E) Cr, Mn, Fe, Co
B) Ne, Ar, Kr, Xe D) C, P, Se, I

51. Pi bonding occurs in each of the following species EXCEPT

A) CO2 C) CN- E) CH4
B) C2H4 D) C6H6

58. Which of the following represents the ground state electron configuration for the Mn+3
ion?

A) 1s22s22p63s23p63d4 C) 1s22s22p63s23p63d24s2 E) 1s22s22p63s23p63d34s2 B) 1s22s22p63s23p63d54s2 D) 1s22s22p63s23p63d84s2

60. Which of the following has a zero dipole moment?

A) HCN C) SO2 E) PF5
B) NH3 D) NO2

66. Ca, V, Co, Zn, As

Gaseous atoms of which of the elements above are paramagnetic?

A) Ca and As only C) Ca, V, and Co only E) V, Co, and Zn only
B) Zn and As only D) V, Co, and As only

70. One of the outermost electrons in a strontium atom in the ground state can be described
by which of the following sets of four quantum numbers?

A) 5, 2, 0, 1/2 C) 5, 1, 0, 1/2 E) 5, 0, 0, 1/2
B) 5, 1, 1, 1/2 D) 5, 0, 1, 1/2
 

80. For which of the following molecules are resonance structures necessary to describe the
bonding satisfactorily?

A) H2S C) CO2 E) PF3
B) SO2 D) OF2

Free Response

8. Discuss some differences in physical and chemical properties of metals and nonmetals.
What characteristic of the electronic configurations of atoms distinguishes metals form
nonmetals? On the basis of this characteristic, explain why there are many more metals
than nonmetals.

9. The diagram shows the first ionization energies for the elements from Li to Ne. Briefly (in
one to three sentences) explain each of the following in terms of atomic structure.

A) In general, there is an increase in the first ionization energy from Li to Ne.

B) The first ionization energy of B is
lower than that of Be.

C) The first ionization energy of O is
lower than that of N.

D) Predict how the first ionization energy
of Na compares to those of Li and of
Ne. Explain.

10. NF3 and PF5 are stable molecules. Write the
electron-dot formulas for these molecules. On the basis of structural and bonding
considerations, account for the fact that NF3 and PF5 are stable molecules but NF5 does
not exist.

11. a. Draw the Lewis electron-dot structures for CO32-, CO2, and CO, including resonance
structures where appropriate.

b. Which of the three species has the shortest C-O bond length? Explain the reason for
your answer.

c. Predict the molecular shapes for the three species. Explain how you arrived at your
predictions.



 


Answers


 


22.    E
40.    A
41.    A
43.    D
51.    E
58.    C
60.    E
66.    D
70.    E
80.    B

Free Response

8.    Most metals contain d orbitals which are being filled.  Non-metals have p orbitals as their highest occupied orbitals.  Since there are more d orbitals than p orbitals, there ends up being more metals than non-metals.

9.    A.    Ionization energy increases due to an increase in nuclear charge (i.e. more protons) and the fact that the electron shielding is remaining relatively constant across a period.

        B.    Be's outer e's are in a 2s orbital.  B's outer e is in a 2p orbital which is shielded from the nucleus by the 2s orbital.  Therefore, the ionization energy is less.

        C.   Nitrogen has a half filled p orbital, oxygen does not.  Half filled orbitals are a little more stable, therefore it is easier to pull the e away from oxygen, therefore oxygen has a lower ionization energy.

        D.    Na will have a lower ionization energy than both Li and Ne for reasons discussed above...

10.    PF5 exceeds the octet rule.  This is allowed because it is in the 3rd row (i.e. it has d orbitals available.).  N is in the second row and therefore cannot exceed the octet rule.

11.abc

CO32- has a resonance structure which makes each bond about a 1 1/3 bond.  Shape = trigonal planar.
CO2 is linear with a double bond to each oxygen.
CO is linear with a triple bond between C and O.

Therefore, CO has the shortest bond, CO2 the next shortest, and CO32- the last.