topic 2 Flashcards

1
Q

what is ionic bonding

A

oppositley charged ions held together by electrostatic attraction

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2
Q

how to work out ionic formula

A

write two ions
Ca 2+ NO3 -
swap charges
Ca - NO3 2+
drop charges
Ca (NO3)2
simplify
Ca(no3)2

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3
Q

what are the properties of ionic bonds

A

most disolve in water - polar
conduct electricity when molten or disolved - ions free
brittle, layers slide, positive aligned with positive, repel
high mp, strong electrostatic forces

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4
Q

what affects the strength of an ionic bond

A

size of the charge
- bigger charge = stronger electrostatic attraction
- more energy

size of ion
- smaller ion = stronger electrostatic attraction
- ions can pack together more closley
- more energy

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5
Q

what happens to ionic radius down a group and why

A

increases
number of shells increases

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6
Q

what are isoelectric ions

A

diffferent atoms that have same number of electrons

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7
Q

what happens to the ionic radius of isoelectric ions ar atomic number increases and why

A

decreases
more protons pulling electron shells

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8
Q

what evidence is there for charged oartickes including colours and ions

A

electrolysis of copper (II) chromate (VI) on wet filter paper - green

positive Cu 2+ ions move towards -ve cathode - blue

negative CrO4 2- ions move towards +ve anode - yellow

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9
Q

what is covalent bonding

A

sharing of outer electrons to obtain a full shell
electrostatic attraction between shared electrons and +ve nucleus

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10
Q

what is a dative bond

A

one atom dontates 2 electrons

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11
Q

draw the bonding in NH4

A

see covalent bonding flash card

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12
Q

how do bond enthalpy and bond length link

A

shorter bond = higher bond enthalpy

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13
Q

what forces are there in covalent molecules and between what

A

forces of attraction - +ve nucleui and -ve electrons

repulsive forces - 2 +ve nuclei and between electrons of atom

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14
Q

what is bond length in terms of forces

A

balance between attractive and repulsive forces

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15
Q

what happens to the atrractive force, bond length and bond enthalpy when high electron density

A

stronger attraction
shorter bond length
higher bond enthalpy

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16
Q

what is the shape and angle in a moleucle when BP=2 and LP=0 with example and draw

A

linear
180
BeCl2

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17
Q

what is the shape and angle in a moleucle when BP=3 and LP=0 with example and draw

A

trigonal planar
120
BF3

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18
Q

what is the shape and angle in a moleucle when BP=4 and LP=0 with example and draw

A

tetrahedral
109.5
CH4

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19
Q

what is the shape and angle in a moleucle when BP=5 and LP=0 with example and draw

A

trigonal bipyramidal
90 and 120
PCl5

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20
Q

what is the shape and angle in a moleucle when BP=6 and LP=0 with example and draw

A

octahedral
90
SF6

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21
Q

what is the shape and angle in a moleucle when BP=3 and LP=1 with example and draw

A

trigonal planar
107
NH3

22
Q

what is the shape and angle in a moleucle when BP=2 and LP=2 with example and draw

A

bent
104.5
H2O

23
Q

what is the shape and angle in a moleucle when BP=3 and LP=2 with example and draw

A

distorted t
87.5
ClF3

24
Q

what is the shape and angle in a moleucle when BP=4 and LP=1 with example and draw

A

seesaw
87 and 102
SF4

25
Q

what is the shape and angle in a moleucle when BP=5 and LP=1 with example and draw

A

square pyramidal
81.5 and 90
IF5

26
Q

what is the shape and angle in a moleucle when BP=4 and LP=2 with example and draw

A

square planar
90
XeF4

27
Q

describe the structure and properties of diamond

A

each carbon bonded 4x in tetrahedral shape
heat conducts - tightly packed rigid arrangement
very high mp - strong covalent bonds
doesnt conduct electricity - no delocalised electrons
insoluble - covalent bonds too strong

28
Q

decribe the structure and properties of graphite

A

each carbon bonded 3x with 4th electron delocalised
layers slide - weak forces between layers
conducts electricity - delocalised electrons between layers
low density - layers far apart
high mp - strong covalent bonds
insoluble - strong covalent bonds

29
Q

decribe the structure and properties of graphene

A

1 layer of graphite
hexagonal carbon rings
conducts electricity - delocalised free moving electrons
high strength - delocalised electrons
light weight and transparent - one cell thick

30
Q

what is metalic bonding

A

positive methal ions are formed as metals donate electrons to form sea of delocalised elctrons
electrostatic attraction between +ve metal ions and delocalised electrons
more elctrons an atom can dontae the higher the mp

31
Q

what are the properties of metalic bonds

A

good thermal conductors - delocalised e- transfer kinetic energy
good electrical conductors - delocalised e- are mobile and can carry current
high mp - strong electrostatic attractions
insoluble - metalic bonds strong
malleable and ductile - ion layers can slide and still retain at5tractionw

32
Q

hat is electronegativity

A

ability for an atom to attract electrons towarrds itself in a covalent bond

33
Q

where are the most elecronegative elements on the periodic table

A

up and right

34
Q

what scale measures electronegativity

A

pauling

35
Q

how do ionic bonds and electronegativity link

A

biggger difference more ionic the compound

36
Q

what is a polar bond

A

covalent bonds become polar if atoms have a difference in elecronegativity
eg HCl H2O

37
Q

when are compounds not polar

A

same electronegativity
polar bond stmmetrical eg CO2

38
Q

what are london forces

A

weakest intermolecular force
exist between atoms
ant molecule with electrons can form a dipole
temporary dipole when 2 molecules neare
electrons in one molecule can move from one end to another

39
Q

who do london forces hold some molecules in crystal structure

A

iodine

weak london forced hold I2 molecules
strong covalent bonds hold the 2 atoms

40
Q

what affects size of london force

A

size of atom
bigger = larger e- cloud = more london forces

41
Q

what is a dipole dipole intermolecular force

A

exisit in molecules with polarity
eg HCl

42
Q

what is the test for a dipole dipole

A

placing a charged rod near steadt stream of polar liquid
bend towards

43
Q

what is a hydrogen intermoleular force

A

strongest
very electronegative elements
- hydrogen with nitrogen, oxygen or flurine

44
Q

what differes in the hydrogen bonding of water and ice

A

ice forms a regular structure, the molecules are further apart making it less dense

45
Q

why are alcohols not as volatile as alkanes

A

hydrogen bonding in alcohols

46
Q

what solvents do polar molecules dissolve in

A

polar solvents

47
Q

what must happen for a substance to dissolve

A

solvent binds must break
substance bonds must break
new bonds formed between substance and solvant
new bonds of same or greater strength

48
Q

what is hydration and draw diagrams

A

water molecules surrond ion
see flash card

49
Q

do alcohols dissolve

A

dissolve in polar solvants as they can hydrogen bond
hydrocarbon doesnt dissolve
bigger=less soluble

50
Q

do haloalkanes dissolve

A

no as dipoles not strong

51
Q

what are non polar substances and what dissolve in them

A

only have london force

alkenes dissolves as they can form london forces between molecules