Types of Bonds Flashcard

what is the octet rule?
atoms bond with each other in order to have 8 e- in their valence shell.
Give the elements that fall short of the octet rule?

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

Give the elements that fal go beyond the octet rule?
all elements in period 3 or greater
what gives a covalent bond polarity?
the degree to which the  pair of electrons are shared equally or unequally btwn the two atoms

what is a nonpolar covalent bond?

 

if the electron pair is shared equally

 

what is a polar covalent bond?

if the electron pair is shared unequally.

 

(one will have a stronger pull on the e- causing ‘pole’)

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?

 

high melting/boiling point

dissolve in: aqueous/polar solevents

good conductors of electricity

crystalline lattice structure with minimum repulsive forces.

According to the Pauling scale, the difference in electronegativites for 2 atoms must be greater than ____ in order for an ionic bond to occur?
1.7
For atoms with similar electronegativities, why covalent bond? (and not ionic)
Covalent bonding is more energy favorable; forming ions would be too costly.
What is the bonding force in covalent bonds? (aka what keeps the atoms together)
there is an are attraction that each electron in the shared pair has for the 2 positive nuclei of the bonded atoms.

what are some of the physical charactersitics of  covalent compounds?

(high/low) boiling pt, melting pt.

can they conduct electricity?

 

 

low  boiling pt, melting pt.


poor conductors of electricity.

Bond lenghth  def

avergage distance bwtn 2 nuclei, 

 

if the # of shared e increases the bond lenghth will
decrease

who has the highest bond length?

who has the highest bons strenghth?

  • triple bond: 

length: short

strength: strongest

  • double bond:

length: medium

strength: medium

  • single:

length: longest

strength: weakest

what are the diatomic atoms?

HONCl BRIF

hydrogen

oxygen

nitrogen

chlorine

bromine

iodine

fluorine

describe the dipole moment of a polar covalent bond

ex HCl

H will have a slightly positive charge(less electronegative)

Cl will have a slightly negative charge (pulling the electrons b/c its more electronegative)

what types of compounds are usually involved in coordiate covalent bonds?

lewis acid (accepts e) (electrophile)

ex BF3

lewis base (donated e) (nucleophile)

 

ex NH3

t/f :

a lewis structure with small or no formal charges is preferred

true

t/f :

which lewis structure is preffered?

-2-0-+1

N-C-0 

vs

0-0- -1

N-C-0

0-0- -1

N-C-0

 

this has a small seperation  btwn opposite charges

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)

0-0- -1

N-C-0

 

oxygen is the most electronegative atom and can hold the largest negative formal charge

what is the difference btwn molecular geometry and electronic geometry?

 

molecular geometry:

includes only bonding pairs

electronic geometry:

includes bonding & lone pairs

london/dispersion forces def

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.

london/dispersion forces usually occur in  compounds with what type of bonds?

nonpolar convalent bonds

(note: these interactions are in ALL atoms & molecules)

why are dispersion forces considered weakest bonds?

b/c their dipole moments:

can shift anytime

are short lived

short distance only

 

which element would most likely have high dipsersion forces

H vs Cl 

include why

Cl because its electrons are far from nucleus

(larger componds have greater dispersion forces vs smaller ones)

dipole-dipole interactions def
ways in which polar molecules arrange themselves neg and postitive ends are close to each other.
why do polar species tend to have higher melting and boiling pts than nonpolar compounds of the same mass?
b/c polar moloecules are arranged with the opposite charges facing each other, they molecules are held together by an attractive electrostatic force.

describe hydrogen bonding

 

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)

 

 

 

What 3 elements are always cause hydrogen bonds when bonded to hydrogen?

 

hold the F-O-N

Fluorine

Oxygen

Nitrtogen

 

(very electronegative)

List these from highest to lowest boiling point:

acetone

octane

methane

acetic acid

octane (lg branched hydrocarbon)

acetic acid (hydreogen bonds)

water (same)

acetone (dipole)

methane(dispercion forces)

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