Electrons and Bonding Lab

Karen Romine #33651288 Electrons and Bonding Lab

Table 1. H & H- ComparisonH∙ H:-

Density

Density Potential

HOMO

LUMO

Cation Error Message: No electrons in molecule


Table 2. H2+, H2, & H2

- ComparisonSpecies &Equilibrium Bond Length (Å)

HOMO (-1) HOMO & E HOMO

(kJ/mol)

LUMO & E LUMO

(kJ/mol)

LUMO (+1) Density Potential & E (kJ/mol)

H2+

1.049No HOMO -1 because there is only one molecular orbital filled

-2902.48

-1578.38

H2

0.735No HOMO -1 because there is only one molecular orbital filled

-1565.20 438.52-2973.35693

H2-

1.375

65.811643.23

-2592.25


Table 3. Density Surfaces of H2 at Various Bond Lengths Internuclear

Distance (R, Å)Density Surfaces(Gray Mesh Plots)

Internuclear Distance (R, Å)

Density Surfaces(Gray Mesh Plots)

0.400

1.25

0.5803.20

Equilibrium Bond Length(0.743)

5.00


Discussion:1. a. The density images are different in that the nucleus is relatively smaller in H- than in

H because H- has a larger electron cloud on account of having one more electron than H.b. The two density potential images are different in the areas near the outside of the orbital

where you are very likely or unlikely to find an electron. c. HOMO: n=1, l=0d. LUMO: n=1, l=0e. The calculation for H+ failed because there are no electrons in H+ so there was nothing

to calculate

Karen Romine #33651288 Electrons and Bonding Lab2. H2-

MO Configuration: (σ1s)2(σ1s*)1(σ2s)0(σ2s*)0

Bond order: ½

H2

MO Configuration: (σ1s)2(σ1s*)0(σ2s)0(σ2s*)0

Bond Order: 1

σ1s*

σ1s

σ2s

σ2s*

1s1s

2s2s

E

σ1s*

σ1s

σ2s

σ2s*

1s1s

2s2s

E

σ1s*

σ1s

σ2s

σ2s*

1s1s

2s2s

E H2+MO Configuration: (σ1s)1(σ1s*)0(σ2s)0(σ2s*)0

Bond Order: ½

H2 is the most stable because it has the highest bond order and no electrons in antibonding orbitals.

Karen Romine #33651288 Electrons and Bonding Lab3. a. Density is the absolute value of the wave function squared, |ψ|2. The HOMO and LUMO are

the sum of wave functions, Ψ= ψa+ψb.b. If two colors are present on a HOMO or LUMO plot it indicates orbitals with opposite spinsc. The electron is more delocalized in the LUMO plots of both H2+ and H2.d. There is no relationship between HOMO & LUMO and bonding & antibonding orbitals. In H2 and

H2+, the HOMO is the bonding orbital and the LUMO is the antibonding orbital, but this is not true for all molecules. Ground state HOMO & LUMO are determined by how many electrons the molecule has, bonding & antibonding orbitals are solutions to Schrödinger’s equation and depend on quantum numbers.

e. H2- has a HOMO with a node.

f. The 1s atomic orbitals creates the LUMO for H2-. The LUMO orbitals for H2+ and H2 more closely resemble the HOMO in H2-.

g. For H2, the wide band of high density between the two nuclei indicates a stronger bond order of 1. The plot for H2- is similar to H2 but the band of high density between the nuclei is thinner and narrower. For H2+ the areas of high electron density are at spots between the two nuclei, the plot is more generalized than that of H2, and there is some likelihood of finding an electron on the outside of the nuclei rather than between. These details demonstrate a lower bond order of ½ for both H2- and H2+.

h. The HOMO (-1) images for H2+ and H2 didn’t give any surface images because those surfaces do not exist. There is only occupied molecular orbital is the lowest MO the molecule has.

i. The LUMO (+2) orbitals need to be calculated for H2 and H2+.4.

5. At longer bond lengths, the interaction between atomic orbitals becomes small so the electrons are held in atomic orbitals rather than molecular orbitals. Because the molecular orbitals are not filled, the energy difference between the HOMO and LUMO approaches zero.

0.400

0.580

5.003.20

1.25

Equilibrium

Documents

Electrons and Bonding Lab