Term
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Definition
| atoms bond with each other in order to have 8 e- in their valence shell. |
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Term
| Give the elements that fall short of the octet rule? |
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Definition
H: only needs 2 to fill its valence shell(it has a 1s orbital!)
Li: wants 2 more
be: wants 4 more
B:bonds to get 6 |
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Term
| Give the elements that fal go beyond the octet rule? |
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Definition
| all elements in period 3 or greater |
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Term
| what gives a covalent bond polarity? |
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Definition
| the degree to which the pair of electrons are shared equally or unequally btwn the two atoms |
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Term
what is a nonpolar covalent bond?
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Definition
| if the electron pair is shared equally |
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Term
what is a polar covalent bond? |
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Definition
if the electron pair is shared unequally.
(one will have a stronger pull on the e- causing 'pole') |
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Term
what are some of the physical charactersitics of ionic compounds?
(high/low) boiling pt, melting pt.
can they conduct electricity?
what can they dissolve in?
what do they form in solid state?
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Definition
high melting/boiling point
dissolve in: aqueous/polar solevents
good conductors of electricity
crystalline lattice structure with minimum repulsive forces. |
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Term
| According to the Pauling scale, the difference in electronegativites for 2 atoms must be greater than ____ in order for an ionic bond to occur? |
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Definition
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Term
| For atoms with similar electronegativities, why covalent bond? (and not ionic) |
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Definition
| Covalent bonding is more energy favorable; forming ions would be too costly. |
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Term
| What is the bonding force in covalent bonds? (aka what keeps the atoms together) |
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Definition
| there is an are attraction that each electron in the shared pair has for the 2 positive nuclei of the bonded atoms. |
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Term
what are some of the physical charactersitics of covalent compounds?
(high/low) boiling pt, melting pt.
can they conduct electricity?
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Definition
low boiling pt, melting pt.
poor conductors of electricity. |
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Term
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Definition
avergage distance bwtn 2 nuclei,
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Term
| if the # of shared e increases the bond lenghth will |
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Definition
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Term
who has the highest bond length?
who has the highest bons strenghth? |
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Definition
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length: short
strength: strongest
length: medium
strength: medium
length: longest
strength: weakest |
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Term
| what are the diatomic atoms? |
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Definition
HONCl BRIF
hydrogen
oxygen
nitrogen
chlorine
bromine
iodine
fluorine |
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Term
describe the dipole moment of a polar covalent bond
ex HCl |
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Definition
H will have a slightly positive charge(less electronegative)
Cl will have a slightly negative charge (pulling the electrons b/c its more electronegative) |
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Term
| what types of compounds are usually involved in coordiate covalent bonds? |
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Definition
lewis acid (accepts e) (electrophile)
ex BF3
lewis base (donated e) (nucleophile)
ex NH3 |
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Term
t/f :
a lewis structure with small or no formal charges is preferred |
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Definition
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Term
t/f :
which lewis structure is preffered?
-2-0-+1
N-C-0
vs
0-0- -1
N-C-0 |
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Definition
0-0- -1
N-C-0
this has a small seperation btwn opposite charges |
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Term
t/f :
which lewis structure is preffered?
-2-0-+1
N-C-0
vs
0-0- -1
N-C-0
(in reference to where the largest formal charge is placed) |
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Definition
0-0- -1
N-C-0
oxygen is the most electronegative atom and can hold the largest negative formal charge |
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Term
what is the difference btwn molecular geometry and electronic geometry?
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Definition
molecular geometry:
includes only bonding pairs
electronic geometry:
includes bonding & lone pairs |
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Term
| london/dispersion forces def |
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Definition
rapid depopolariztion and counterpolarization of the electron cloud causing the formation of short lived dipole moments
(aka one end becomes negative and an end near by becomes postive, this cycle goes through entire compound. |
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Term
| london/dispersion forces usually occur in compounds with what type of bonds? |
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Definition
nonpolar convalent bonds
(note: these interactions are in ALL atoms & molecules) |
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Term
| why are dispersion forces considered weakest bonds? |
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Definition
b/c their dipole moments:
can shift anytime
are short lived
short distance only
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Term
which element would most likely have high dipsersion forces
H vs Cl
include why |
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Definition
Cl because its electrons are far from nucleus
(larger componds have greater dispersion forces vs smaller ones) |
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Term
| dipole-dipole interactions def |
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Definition
| ways in which polar molecules arrange themselves neg and postitive ends are close to each other. |
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Term
| why do polar species tend to have higher melting and boiling pts than nonpolar compounds of the same mass? |
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Definition
| b/c polar moloecules are arranged with the opposite charges facing each other, they molecules are held together by an attractive electrostatic force. |
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Term
describe hydrogen bonding
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Definition
a specific, strong form of dipole-dipole interactions which may be inter or intra molecular
occur when a hydrogen is bound to highly electronegative atom, its partial positive charge interacts with the partial negative charge (of O,F,N)
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Term
What 3 elements are always cause hydrogen bonds when bonded to hydrogen?
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Definition
hold the F-O-N
Fluorine
Oxygen
Nitrtogen
(very electronegative) |
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Term
List these from highest to lowest boiling point:
acetone
octane
methane
acetic acid |
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Definition
octane (lg branched hydrocarbon)
acetic acid (hydreogen bonds)
water (same)
acetone (dipole)
methane(dispercion forces) |
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