Chemistry 2720 Fall 2000 Assignment 8

Due: Tuesday, Dec. 5, 9:25a.m.

1.

(a)

Nuclear physics predicts that there may be a few relatively stable elements with atomic numbers around 114. What would the ground-state electronic configuration of element 114 (ununquadium, Uuq) be? [4 marks]

(b)

Predict the ion(s) which might be formed by this element and give their ground-state electronic configurations. [4 marks]

Hint: In what group would element 114 be? How does the preceding element in the group behave?

(c)

State whether each of the atom and its ion(s) is paramagnetic or diamagnetic. [3 marks]

2.

The following is an orbital energy diagram (not drawn to scale) for the valence molecular orbitals of the Cr₂ molecule:

(a)

Show the occupancy of the orbitals in the ground state. [4 marks]

(b)

Would you expect Cr₂ to be paramagnetic? [1 mark]

(c)

The lowest-energy valence orbital has the following appearance:

i.

Is this a bonding or an antibonding orbital? Explain briefly. [2 marks]

ii.

Can you explain the shape of this orbital based on LCAO theory? [2 marks]

3.

Which of the following molecules have rotational absorption spectra? Which have rotational Raman spectra? [8 marks]

(a)

N₂

(b)

CO

(c)

NH₃

(d)

CH₄

4.

Rotational absorption lines for ¹H³⁵Cl were found at 2498, 3122, 3739, 4358, 4973, 5583, 6194 and 6801GHz. The atomic masses of ¹H and of ³⁵Cl are 1.0078250321 and 34.96885271amu, respectively. What is the bond length of this molecule? [10 marks]

Bonus: This problem can be solved by doing some straightforward calculations and averaging the results. However, a more accurate value can be obtained by a fitting procedure. One bonus mark may be awarded for successful use of a fitting procedure on these data.