CHEM 110 Lecture Notes - Lecture 14: Lone Pair, Fluorine, Intermolecular Force
Friday, October 6, 2017
Bonds
CHEM 110
-Square Brackets:
•There’s no rule
•Tend to put it if you have a charge, and no [ ] when you have a neutral charge
-Exceptions of the Octet Rule
•Electron deficient (reactive) molecules
•Odd electron species
-Have less than 4 valance electron, can hole less than 8 electrons
-Paramagnetic = “free radicals”
-Astrochemistry
-Resonance Structures:
•“In between”
•Multiple plausible Lewis structures for a molecule
•Only move electrons in lone pairs/multiple bonds, not positions of atoms
•Note double headed arrows
•Keep the atoms in the same place —> move the bonds
•Rules for Writing Resonance Structures
-Only exist on paper
-Only move move electrons in lone par/multiple bonds, not atoms
-All structure must be valid Lewis structures
-The actual structure is a hybrid of all resonance structures.
•Resonance and formal charges example:
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CHEM 110 Full Course Notes
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Document Summary
Square brackets: there"s no rule, tend to put it if you have a charge, and no [ ] when you have a neutral charge. Exceptions of the octet rule: electron de cient (reactive) molecules, odd electron species. Have less than 4 valance electron, can hole less than 8 electrons. Only move move electrons in lone par/multiple bonds, not atoms. All structure must be valid lewis structures. The actual structure is a hybrid of all resonance structures: resonance and formal charges example: Slide 138 and 145- former exam q. Triple bonds are shorter and stronger than double/single bonds. In a planar molecule: there"s a drift of charge from boron to the fluorine, there"s a dipole, 2 of them at angles (120 degrees) Valance shell electron pair repulsion: put valance electron paris as far apart form one another as possible. Molecular geometry: depiction of bond lengths and bond angles.
