CHEM 042 Lecture 4: Lecture 3 & 4
23 Jan 2019
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In writing resonance structures, it is okay to generate a resonance structure with less
than 8 electrons, but not more than 8.
A carbon with 4 single bonds is sp3 hybridized and tetrahedral
VSEPR- atoms in molecules adopt shapes that maximize the distance between valence
shell electron pairs
What orbitals will be involved in bonding?
- For carbon, orbitals are 1s, 2s, 2px, 2py, and 2pz
SP3 hybrid orbitals point toward the 4 corners of a tetrahedral
Bonds and molecules can be polar
Writing formulas and isomerism
Isomers the same yet not the same. The same by one definition and not the same by
another definition.
- Structural or constitutional isomers = same molecular formula, different atom
connectivity.
- Dash structural formulas = every atom and every bond are shown.
Note: we don't violate the octet rule when drawing constitutional isomers.
- Condensed structural formulas = everything “attached” to an atom or bonded to
it, is drawn after it with no bonds shown
- Look up “condensed structural formulas”
Bond line formulas
- Show only the carbon skeleton, and no hydrogens are shown. The number of
hydrogens necessary to complete the valence are assumed to be there (except
on nitrogen and oxygen)
Document Summary
In writing resonance structures, it is okay to generate a resonance structure with less than 8 electrons, but not more than 8. A carbon with 4 single bonds is sp3 hybridized and tetrahedral. Vsepr- atoms in molecules adopt shapes that maximize the distance between valence shell electron pairs. For carbon, orbitals are 1s, 2s, 2px, 2py, and 2pz. Sp3 hybrid orbitals point toward the 4 corners of a tetrahedral. The same by one definition and not the same by another definition. Structural or constitutional isomers = same molecular formula, different atom connectivity. Dash structural formulas = every atom and every bond are shown. Note: we don"t violate the octet rule when drawing constitutional isomers. Condensed structural formulas = everything attached to an atom or bonded to it, is drawn after it with no bonds shown. Show only the carbon skeleton, and no hydrogens are shown.
