Chapter 10: Molecular Geometry and Chemical Bonding Theory Flashcards
What is an isomer?
The same compound that can have a different arrangement of atoms.
What are the two arrangments of isomers?
Cis: Atoms are on the same side
Trans: Atoms are on opposite sides
What is molecular geometry?
The general shape of a molecule, as determined by the relative positions of the atomic nuclei
What is the valence-shell electron-pair repulsion model (VSEPR)?
Predicts the shapes of molecules and ions by assuming that the valence-shell electron pairs are arranged about each atom so that electron pairs are kept as far away from one another as possible and minimizes electron-pair repulsions.
Hw do you predict the increase or decrease in bond angles?
A lone pair tends to require more space than a corresponding bonding pair.
A lone pair of electrons is attracted to only one atomic core where a bonding pair is attracted to two. As a result the lone pair is more spatially diffuse.
Do multiple bonds require more or less space than single bonds because of the greater number of electrons?
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What is a dipole moment?
A quantitative measure of the degree of charge separation in a molecule and is therefore an indicator of the polarity of the molecule.
A positive charge “q” and a negative charge “-q” are separated by distance “d” has a dipole moment “u”
u = q x d
How are dipole moments measured?
They are easured in units of debyes (D) and 1D is = 3.34 x 10^-30 cm
What is valence bond theory?
An approximate theory to explain the electron pair or covalent bond by quantum mechanics
What occurs during valence bond theory?
A bond forms between two atoms when:
- An orbital on one atom comes to occupy a portion of the same region of space as an orbital on the other atoms (overlap)
- The total number of electrons in both orbitals is no more than two
What are the different forms of a multiple bond?
Sigma bond: Has a cylindrical shape about the bond axis
Pi bond: Has an electron distribution above and below the bond axis.
