CHMA11H3 Chapter Notes -Ideal Gas, Equilibrium Constant, Ideal Gas Law

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CHMA11H3 Full Course Notes

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10. 2 vespr theory: the five basic shapes (400-403) Valence shell electron pair repulsion (vespr) theory: allows prediction of shapes of molecules based on idea that electrons- either as lone pairs or as bonding pairs- repel one another. Based on idea that electron groups repel one another through coulombic forces. Electron groups: lone pairs, single bonds, multiple bonds, or lone electrons in a molecule repulsions between electron groups on interior atoms of a molecule determine geometry of molecule. Preferred geometry of a molecule is one where electron groups have max separation (min energy) possible for molecules with one interior (central) atom, molecular geometry depends on. Number of electron groups around central atom. Molecules that form only 2 single bonds, with no lone pairs, rare because they don"t follow octet rule. Double bond contains more electron density than single bond, exerts slightly greater repulsion on single bonds. Octahedral geometry: molecular geometry of 7 atoms with 90 bond angles.

Related Questions

Select all molecular geometries (shapes) that are possible for a molecule with five electron groups an the central atom.

Do not include molecular geometries that can only be produced by having a single bonding group on the central atom (all but one of the electron groups are lone pairs.)

ocahedral
	T-shaped
	linear
	bent
	trigonal pyramidal
	trigonal bipyramidal
	seesaw
	square pyramidal
	trigonal planar
	tetrahedral
	square planar

1.) Which of the following statements is true concerning thegeometries of CF4 and NF3?
___The two molecules have the same molecular geometry.
___The two molecules have the same molecular geometry but differentelectron pair geometries.
___The two molecules have different electron pair geometries.
___The two molecules have the same electron pair geometry butdifferent molecular geometries.

2.) When there are 3 lone pairs around the central atom with 5electron pairs, the lone pairs occupy which of the following?
___all axial positions
___one axial and two equatorial positions.
___two axial and one equatorial positions
___all equatorial positions

3.) When the lone pair of electrons in SF4 is placed at theequatorial position, which of the following is true?
___The molecular geometry is trigonal bipyramidal.
___There are no bonding pairs at 90Â° angles to each other.
___The lone pair has 2 bonding pairs at 90Â° and 2 at 120Â°angles.
___There are larger repulsions.

4.) Which molecule has only 90Â° and 180Â° bond angles and one lonepair of electrons on the central atom?
___XeF4
___SeF4
___BCl3
___ClF5

5.) Which of the following has all idealized bond angles justslightly less than 120Â°?
___BF3
___NH3
___SF6
___ClF3

Use valence bond theory to describe the bonding and geometry in theSeF4 molecule.

A. The central atom is Se, which has five electron groups around it(four bonding pairs and one nonbonding/lone pair). Theelectron-group geometry is trigonal bipyramidal (and the moleculargeometry is see-saw). To facilitate this geometry, the Se atom'sorbitals are hybridized as sp3d orbitals. Four of these hybridorbitals contain one of Se's 6 valence electrons each, and thesehybrid orbitals overlap with unhybridized p orbitals of the four Fatoms. The fifth hybrid orbital of Se contains a lone pair ofelectrons. There are 4 sigma bonds and 0 pi bonds in thismolecule.
B. The central atom is Se, which has six electron groups around it.The electron-group geometry is octahedral. To facilitate thisgeometry, the Se atom's orbitals are hybridized as sp3d2 orbitals.Four of these hybrid orbitals contain one of Se's 6 valenceelectrons each, and these hybrid orbitals overlap with unhybridizedp orbitals of the four F atoms. The fifth and sixth hybrid orbitalsof Se contain lone pairs of electrons. There are 4 sigma bonds and0 pi bonds in this molecule.
C. The central atom is Se, which has four electron groups aroundit. The electron-group geometry is tetrahedral. To facilitate thisgeometry, the Se atom's orbitals are hybridized as sp3 orbitals.These hybrid orbitals overlap with unhybridized p orbitals of thefour F atoms. There are 4 sigma bonds and 0 pi bonds in thismolecule.
D. The central atom is Se, which has four electron groups aroundit, two single bonds and two double bonds. The electron-groupgeometry is tetrahedral. To facilitate this geometry, the Se atom'sorbitals are hybridized as sp3 orbitals. These hybrid orbitalscontain one electron each of Se's 6 valence electrons, and thesehybrid orbitals overlap with unhybridized p orbitals of the four Fatoms. The final 2 electrons of Se's 6 valence electrons reside inunhybridized p orbitals, which overlap with unhybridized p orbitalsof the F atoms. There are 4 sigma bonds and 2 pi bonds in thismolecule.

CHMA11H3 Chapter Notes -Ideal Gas, Equilibrium Constant, Ideal Gas Law

CHMA11H3 Full Course Notes

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