Advanced Inorganic Chemistry

Test 1

Name:  ________________________                                                                  February 22, 2017

141 possible

1.   (2 pts)  What is the second most abundant element in the universe?

Helium

2.   (2 pts)  What is the nucleon number of ?  (Give a number.)

235

3.   (2 pts)  N-14 and N-15 are isotopes of nitrogen.  What term describes the relation between and ?

nuclides

4.   (18 pts)  Calculate the binding energy per nucleon of fluorine-19, 19F, in MeV.  The mass of F-19 is 18.99840 u (u is atomic mass units).

particle

mass /u

neutron

1.008665

 

proton

1.007277

 

electron

0.000548

 

u ® kg

1.66054 ´ 10-27

 kg/u

c

2.99793 ´ 10+8

 m/s

J ® eV

1.60218 ´ 10-19

 J/eV

The mass of 10 neutrons, 9 protons, and 9 electrons is 19.157075 u.  5 pts

The difference is 0.158675 u.  Converting to kg gives 2.63486 ´ 10-28 kg.  2 pts

Using E = mc2 gives 2.36810 ´ 10-11 J.  5 pts

Converting to MeV gives a binding energy of 147.805 Mev.  3 pts

And, dividing by 19 gives the binding energy per nucleon, -7.77919 MeV.  (The negative sign isn’t necessary.)         3 pts

This page:  24 pts


 

5.   (4 pts)  Which two elements are the most stable?  ______________ iron and nickel

6.   (2 pts)  Give an example of an element that is apt to undergo fussion:  ____ H, e.g.; anything lighter than Fe.

7.   (3 pts)  In carbon dating, the C-14 in plants is measured.  Which molecule contains the C-14 that gets absorbed by plants? ____________carbon dioxide.

8.   (13 pts)  Sketch the shapes of the five d orbitals, and label them.  Indicate the sign of the wavefunction on the lobes. 

The shading indicates the sign of the wavefunction.     5 pts, shapes; 5 pts labels; 3 pts signs.

 

9.   (3 pts)  Which of the following is true regarding the electron affinity of an anion?

a)      It is favorable because anions are usually large (except for F), and so the negative charge is spread out.

b)      It is favorable because anions tend to be fairly electronegative.

c)      It is favorable because the wave function of the anion overlaps with the electron.

d)      It is unfavorable because of repulsion between the anion and the electron.

e)      It is unfavorable because only cations release energy when they accept electrons.

10. (2 pts)  How many nodes are in the angular part of the wavefunction of a 5f orbital?

3

11. (2 pts)  How many nodes are in the radial part of the wavefunction of a 5p orbital?

3

12. (6 pts)  Give the ground-state electron configuration of the following.  Nobel gas abbreviations may be used.

(a)   Cr        [Ar] 4s13d5

(b)   Ge4+    [Ar]3d10  -2 pts for [Ar]3d84s2

This page:  35 pts


 

13. (3 pts)  The radial distribution function on the right could describe which of the following orbitals?

a)      Text Box: 4πr2R(r)21s

b)      2s

c)      2p

d)      3d

e)      5d

14. (3 pts)  Which of the following is the best description of the two orbitals on the right?

a)      B is more penetrating than A and is more shielding.

b)      B is less penetrating than A and is more shielding.

c)      B is more penetrating than A and is less shielding.

d)      B is less penetrating than A and is less shielding.

e)      B is equally as penetrating as A, and equally as shielding.

     (c)   + _____ ®  + 5          

15. (2 pts)  Which element is the “first” chalcogen?

Oxygen.

 (c)   + _____ ®  + 5          

16. (2 pts)  Give an example of a congener of calcium.

Any other group 2 metal

figure 2-0217. (4 pts)  A Ketelaar triangle can be used to predict the type of bonding in a compound.  For Al2O3, the electronegativity of Al is 1.61, and of O is 3.44.  Calculate the following:

Δχ:  _____ 1.83

χmean:  ____ 2.525. 

Place a mark (make it easy to spot) on the Ketelaar triangle in the correct location.

The mark is close to the borderline between ionic and covalent bonding.

This page:  14 pts

18. (3 pts)  Identify the following on the diagram on the right.

a)      LUMO

b)      HOMO

c)      Frontier orbitals

19. (3 pts)  Add arrows representing the following on that diagram.

a)      Ionization energy, I

b)      Electron affinity, Ea

c)      Electronegativity, χ

S4020. (10 pts)  The figure on the right shows the first ionization energies for the first 10 elements in the periodic table.  In going from N (atomic number 7) to O (atomic number 8), I decreases. 

      Using boxes, sketch the electron configuration of N and O, both before and after ionization.  Use your sketch to account for the decrease in ionization energies.

In N, the electron is removed from a half-filled 2p orbital; this is unfavorable because half-filled orbitals have an extra stability.  In O, the electron is removed from a 2p orbital, resulting in the 2p orbitals becoming half-filled; this is favorable.  Consequently, it is easier to ionize oxygen and harder to ionize nitrogen than might be expected.

This page:  16 pts

 

21. (2 pts)  The lanthanide contraction is a result of which orbitals being completely filled?

f-orbitals.

22. (2 pts)  The second electron gain enthalpy refers to the following reaction:  X(g) + e(g) ® X2–(g).  For which elements is this reaction exothermic?

a)   No elements                b)     O             c)     O and S   d)     O, S, and Se

23. (5 pts)  Draw the Lewis structure of SF4.

structure 2-19

24. (4 pts)  Sketch the shape of SF4.

structure 2-20

25. (2 pts)  Identify in your sketch the axial and equatorial substituents.

26. (8 pts)  a)  Draw the Lewis structure of SO2.  Include resonance structures.

 

(2 pts)  b)  What is the name of the shape of SO2?           Angular (or bent)

Answer has to agree with Lewis structure.

27. (3 pts)  Indicate in a sketch a distortion from ideal geometry that is found in the structure of SO2.

The O–S–O is < 120°.

28. (2 pts)  What is the hybridization of the central S in the above structure?

sp2

This page:  30 pts


 

29. (15 pts)      Construct a molecular orbital diagram for O2.  Include labels, such as 2s and σg. 

The diagram should look something like the following.

4 pts for showing atomic orbitals

30. (3 pts)  What is the bond order of O2, according to your diagram?  Show your calculation.

b. o. = ½(bonding – antibonding) = ½(8 – 4) = 2

31. (1 pts)  According to your MO diagram, is oxygen paramagnetic or diamagnetic?

Paramagnetic

32. (3 pts)  Sketch the shape of a σ* molecular orbital.

Something like this:  File:Bonding and antibonding orbital pictures for H2.tiff

This page:  22 pts