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how molecules stick together Flashcards

1
Q

how do molecules have linear shapes

A

if bonding pairs are in negative charge cloud because electrons repel each other and move away from each other as far as possible

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2
Q

shapes of molecules with 2 electron pairs

A

linear shape

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3
Q

bond angle

A

angle between 2 bonds to identify same shaped molecules

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4
Q

bond angle of linear shapes

A

180

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5
Q

molecules name and shape and angle with 3 bond pair electrons

A

-trigonal planar
120 degrees

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6
Q

molecules name and shape with 4 electron pairs

A

109.5 degrees
tetrahedral

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7
Q

ammonia bond angle

A

107

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8
Q

bond angle in water

A

104.5

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9
Q

bond angle when there is lone pair with bond pair

A

bond angle decreases

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10
Q

why does bond angle decrease with lone pair and bond pair

A

lone pair charge cloud wider than bond pair charge cloud
-repel more than bonding pairs
-distance between bonding pairs decreases

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11
Q

order of electron pair repulsion biggest to smallest

A

lone pair lone pair
lone pair bond pair
bond pair bond [air

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12
Q

VESPR

A

valence electron shell repulsion theory
-predicting shapes of molecules

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13
Q

molecule with 2 bonding pairs and one lone pair

A

shape is bent
angle 118

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14
Q

molecule with 3 bond pairs and 1 lone pair

A

shape trigonal pyramidal
bond angle 107

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15
Q

water with 2 bonding pairs and lone pairs shape and angle

A

-bent
angle 104.5

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16
Q

molecule with 5 electron bonding pairs shape and angle

A

trigonal bipyrymidal
-120 and 90

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17
Q

molecule with 4 bonding pairs and 1 lone pair

A

-seesaw FML
-100 and 85

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18
Q

molecule with 3 bonding pairs and 2 lone pairs

A

t shaped
88 degrees

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19
Q

molecule with 3 bonding pairs and 2 lone pairs shape and angle

A

linear
180

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20
Q

molecule with 6 bonding electron pairs

A

-90 degrees
octahedral

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21
Q

molecule with 4 bonding pairs and 2 lone pairs

A

-lone pairs opposite
-90
-square planar

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22
Q

predicting shape of molecule when electron pairs not given

A

-electron pairs repel as much as possible
-draw dot and cross
count how many electron pairs bonding and lone
-identify shape
-add atoms and lone pairs

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23
Q

shapes of molecules with double bonds

A

-double bonds dont repel each other
linear arrangement
-180

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24
Q

how to know if molecule polar

A

if polar bonds
dipole
so molecule polar
bonds on same side of molecule

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25
what happens if bonds not on same side of molecule
-dipoles cancel oout when following vectors of bond charges
26
if all atoms around central atom all same polar or not
if all same molecule non polar if all same and dipoles dont cancel out molecule is polar
27
dipole dipole forces
when attractive force bwteeen oppoiste charges of molecules is dipole dipole forces partial charges
28
how does dipole get stronger
as charge difference increases
29
when does hydrogen bonding occur
when hydrogen is covalently bonded to nitrogen, oxygen or fluorine
30
drawing hydrogen bonds
partial charges lone pairs draw hydrogen to lone pairs from all water molecules or whatever molecules on a strraight line2 hydrogens to 0 lone pair
31
hydrogen bonding in water
-large difference in electronegativuty between hydrogen and oxygen -causes H to have strong positive and O to have strong negative -strong positive attracts lone pair of O -neighouring atoms attracted to positive partial charge
32
temporary dipoles
movement of electrons of non polar molecules means electrons can move and no longer have dipole so dipole temporary
33
induced dipole
both charges on molecule so molecule with dipole repels electrons on negative side and move across molecule so negative side becomes positive so attracted molecules
34
van der waal forces
arise when movement of electrons in one molecule creates a temporary dipole -this induced dipole in a nearby molecule -results in the attraction between partial charges of nearby molecules
35
what do all polar molecules have
dipole di[pole forces van der waal forces
36
van der waal force strength down a group
fluorine has less electrons than iodine so less likely of even dispersion of electrons as more stronger charge difference
37
comparing boiling and melting points
-what bond present -strength of bonds
38
why dont molecular liquids and gases conduct electricity
-when heated intermolecular forces weaken but covalent bonds dont break so electrons not free to move between molecules and carry charge
39
why is ice less dense than water
-hydrogen bonds that hold water molecules move further away from each other to make structure called open lattice structure
40
macromolecules
large molecules with covalent bonds
41
lattice made up of macromolecules
called a marcomolecular or giant covalent lattice
42
what a lattice made up of smaller molecules
molecular lattice
43
forces between chain marcomolecules
between chains
44
forces between sheet macromolecules
between sheets
45
large macromolecules like diamond
covalent bonds no intermolecular forces
46
diamond
macromolecular lattice held together by covalent bonds
47
graphite
marcomolecular lattice bonded to 3 carbons each and graphene sheets held together by weak van der waal forces
48
allotropes
different structures that can form when atoms of that element bond together
49
allotropes of carbon
diamond coal graphene graphite buckminsterfullerene nanotubes
50
how does graphite have 3 bonds carbon
p orbital line in sheet how pi overlap sigma bonds -p overlap strong bonds like double bonds but not 1 spare electron from p orbital is delocalized
51
why does diamond not conduct electricity
all of diamonds outer electrons are in covalent bonds so no delocalised electrons
52
why can graphite conduct electricity
has delocalized electrons so can move freely throughout each layer and carry a charge
53
hardness comparison of graphite and diamond
diamond very hard - drills graphite very soft- pencils
54
melting points of diamond and graphite
very high for both
55
why does graphite have such a high melting point
have to break covalent bonds as well as intermolecular forces
56
representing diamond n
C (s)
57
why are marcomolecukles represented using empiricla formila
number of atoms doesnt effect properties of macromolecule
58
mettalic bonding
-metallic lattice -made up of delocalized electrona and cations -held together by electrostatic forces between cations and delocalized electrons high melting points low solubility -conduct electricity when solid and liquid malleable -ductile
59
ionic bonding
-ionic lattice cations and anions held together by electrostatic forces between cations and anions high melting points usually high solubility consustc electricity when dissolved in water -brittle
60
molecular lattices covalent bonding
-fewer than 1000 atoms -intermolecular forces low melting points varying solubility never conducts electricity
61
giant structures
metallic ionic macromoleciar structures
62
what happens when ionic substances dissolve in water
ions in lattice separate and surrounded by sphere of water molecules -ions surrounded by water molecules are hydrated ions
63
ion dipole
when hydrated ions stick to water molecules
64
water of crystalisation
water molecules woven into salt lattice
65
representing water of crystalisation
other molecules inlattice with dot and number of water molecules present to show how many per other molecule in lattice and that water regularly in lattice
66

physical chem (14 decks)

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