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Mickie515 Mickie515
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10 years ago
(for the smallest bond angle)
1. see saw = square pyramidal < tetrahedral
2. see saw< tetrahedral < square pyramidal
3. square pyramidal < tetrahedral < see-saw
4. tetrahedral < square pyramidal < see-saw
5. tetrahedral < square pyramidal = see-saw
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wrote...
10 years ago
The textbook uses the same question as an example on page 310, step by step, with the answer right there.
wrote...
10 years ago
see saw  bond angles = 90°, 120°, 180°
tetrahedral bond angles = 109.5°
square planar bond angles = 90° 180°

You see the bond angles are not just one angle but up to three angles for the shapes of the molecules.  To compare them in order of increasing bond angle is going to be inconclusive.

If we go by the greatest bond angle, then the order is: 5. tetrahedral < square pyramidal = see-saw

If we go by the minimum bond angle, then the order is: 1. see saw = square pyramidal < tetrahedral

This is the best I can do.  Hope this helps.  Look at the 2nd link for confirmation.
wrote...
10 years ago
Seesaw molecules behave similarly to trigonal bipyramidal ones in that they go through a phase of Berry pseudorotation. The four atoms in motion act as a lever about the central atom; for example, the four fluorine atoms of sulfur tetrafluoride rotate around the sulfur atom.
The molecular geometry can be determined by various spectroscopic methods and diffraction methods. IR, microwave and Raman spectroscopy can give information about the molecule geometry from the details of the vibrational and rotational absorbances detected by these techniques. X-ray crystallography, neutron diffraction and electron diffraction can give molecular structure for crystalline solids based on the distance between nuclei and concentration of electron density. Gas electron diffraction can be used for small molecules in the gas phase. NMR and FRET methods can be used to determine complementary information including relative distances, [3][4][5] dihedral angles, [6] [7] angles, and connectivity. Molecular geometries are best determined at low temperature because at higher temperatures the molecular structure is averaged over more accessible geometries (see next section). Larger molecules often exist in multiple stable geometries (conformational isomerism) that are close in energy on the potential energy surface. Geometries can also be computed by ab initio quantum chemistry methods to high accuracy. The molecular geometry can be different as a solid, in solution, and as a gas.
The position of each atom is determined by the nature of the chemical bonds by which it is connected to its neighboring atoms. The molecular geometry can be described by the positions of these atoms in space, evoking bond lengths of two joined atoms, bond angles of three connected atoms, and torsion angles (dihedral angles) of three consecutive bonds.
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