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20 Cards in this Set
- Front
- Back
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chemical bonds |
interactions that hold ions, atoms, and molecules together |
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Lewis |
noble gases inert due to unique electron configuration; atoms combine to form stable electron configuration; maximum stability results when atom is isoelectric; valence electrons are important; Ocetet rule |
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core electrons |
not normally involved in chemical bonding; held tightly to nucleus; do not take part in bonding |
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Lewis Dot Symbols |
symbol of element representing the nucleus and core electrons and 1 dot for each valence shell electron of element or ion formed by element |
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valence |
electrons normally involved in bonding; number of unpaired electrons of the atom; ground state and valence state are not equal - due to hybridization |
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Ocetet Rule |
atoms tend to gain, lose or share electrons until each have 8 outer shell electrons (not always valence) |
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ionic bond |
metal atom loses all valence shell electrons and nonmetallic atom gains these electron; results in isoelectric valence shell; anions and cations attracted by Coulombic intereactions; EN> or = 2.0 |
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cations |
metals with low ionization energy |
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anions |
nonmetals with high ionization energy (and higher electron affinities) |
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covalent bonds |
electron sharing in forms of bonding pairs; lone pairs describe electron pairs not involved in bonding; usually occurs b/w 2 nonmetal atoms |
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bond-order |
number of bonds joining any 2 atoms |
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nonpolar covalent |
when atoms are identical or share electrons in bond perfectly; bond is 100% covalent; EN < or =0.4 |
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polar covalent |
unequal electron densities; bond is not 100% covalent - has some ionic properties due to unequal sharing; 0.4 |
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partial negative |
area with great electron density |
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partial positive |
area with low electron density |
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electronegativity |
indicates atom's ability to compete for electrons with other atoms to which it is bonded; measured in relation to electronegativity of other elements; related to ionization energy and electron affinity - elements with high ionization energy and high electron affinity will have high electronegativity value |
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methods for looking at electrons |
formal charges and oxidation numbers |
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oxidation number |
used when bond is assumed 100% ionic |
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formal charge |
used when bond is assumed 100% covalent and which atom arrangement is best; charge on atom resulting from the difference between valence electrons in an isolated atom - number of electrons assigned to that atom in Lewis structure; sum must equal total charge on atom/molecule |
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rules for formal charges |
formal charges should be as small as possible (not stable if large); negative formal charge will be on more EN atom; structure with more than +1 formal charge is usually wrong; formals charges of same sign on adjacent atoms are unlikely |
