Chapter 9
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Created by:
GalacticArmada on July 5, 2012
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25 terms
Terms | Definitions |
|---|---|
 covalent bond | chemical bond resulting from the sharing of valence electrons |
| molecule | formed when two or more atoms bond covalently; all molecules are a result of covalent bonds |
| Lewis structure | use electron-dot diagrams to show how electrons are arranged in molecules |
| sigma bonds | single covalent bonds; occur when the electron pair is shared in an area between the two atoms |
| pi bond | formed when parallel orbitals overlap to share electrons |
| endothermic reaction | greater amount of energy is required to break the existing bonds in the reactants |
| exothermic reaction | greater amount of energy is released forming new bonds (more in products) |
| bond length | distance between two bonding nuclei at the point of maximum attraction; determined by size of atoms and number of electron pairs shared |
| bond disassociation energy | amount of energy required to break a specific covalent bond |
| photoelectric effect | photoelectrons (electrons) are emitted from a metal's surface when electromagnetic radiation of a certain frequency shines on it. photoelectrons will never be emitted when radiation of lower frequency shines on the metal. |
| oxyacid | any acid that contains acid and an oxyanion |
| determining lewis structures | regular procedure |
| step 1 | predict the location of certain atoms |
| step 1a | hydrogen is always a terminal, or end, atom. it is only connected to one other atom (it can only share one pair of electrons) |
| step 1b | the atom with the least attraction for shared electrons is in the center. it is usually closer to the left on the periodic table. all other atoms become terminal atoms. |
| step 2 | ~find the total number of electrons available for bonding. this total is the number of valence electrons in the atoms in the molecule. |
| step 3 | determine the number of bonding pairs by dividing the number of electrons available for bonding by two. |
| step 4 | place one bonding pair (single bond) between the central atom and each of the terminal atoms. |
| step 5 | subtract number of pairs in step 4 from the number of bonding pairs in step 3. remaining electron pairs include lone pairs as well as pairs used in double and triple bonds. lone pairs should be placed around each terminal atom bonded to the central atom to satisfy the octet rule. extra pairs are assigned to the central atom. |
| step 6 | the central atom does not have an octet if it is not surrounded by four electron pairs. one or two of the electron lone pairs on the terminal atom must be converted to a double bond or triple bond between the terminal and central atom. usually, carbon, nitrogen, oxygen, and sulfur can form double or triple bonds with the same element or another element. |
| resonance | condition that occurs when more than one valid lewis structure can be written for a molecule or ion. |
| coordinate covalent bond | forms when one atom donates a pair of electrons to be shared with an atom or ion that needs two electrons to be stable |
| VSEPR model | Valence Shell Electron Pair Repulsion model |
| hybridization | atomic orbitals are mixed to form new, identical hybrid orbitalss |
| polar covalent bond | bond resulting from unequal share of electrons |
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