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inorganic chemistry > p block(B fam) > Flashcards

p block(B fam) Flashcards

1
Q

does He belongs to p block?

A

no (s block)

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2
Q

oxdtn state (max oxn state)

A

grp no - 10

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3
Q

max oxn state

A

ns electrons + np electrons

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4
Q

oxides of non metals

A

acidic

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5
Q

oxides of metals

A

basic

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6
Q

highly reactive non metals + highly reactive metals

A

ionic compounds

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7
Q

highly reactive non metals + highly reactive non metals

A

covalent compounds

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8
Q

max covalency of first members is limited to 4 due to

A

abscence of d orbital

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9
Q

first member has a unique tendency to form Ppi-Ppi bonds with itself and others due to

A

small size
absence of d orbital

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10
Q

heavier elements forms _____ bonds instead of ppi-ppi bonds

A

dpi-ppi.
dpi-dpi.

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11
Q

heavier among alkali grp

A

Fr

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12
Q

heavier among chalcogens

A

Po

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13
Q

heavier among noble gases

A

Rn (rad.act.noble)

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14
Q

heavier among alkaline earth metals

A

Ra (rad.act.alk.ear.met)

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15
Q

a hard black coloured non metal

A

boron

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16
Q

aluminium and others are

A

soft metals

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17
Q

why boron is hardest

A

it exist as B12 units
icosahedral sturcture
20 trrigonal face
12 cornes

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18
Q

isotopes of boron

A

B10 (19%)
B11(81%)

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19
Q

Boron exist in crystalline and amorphous forms.then their reactivities..

A

crystalline - inert due to strong structure.
amorphous - little reactive.

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20
Q

boron does not react with whom.

A

cold water,hot water,non oxidising acids(HCl,aq.alkali)

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21
Q

boron react with whom to give

A

molten alkali to form borates

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22
Q

3rd most abundant element and most abundant in the eraths crust

A

aluminium

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23
Q

order of abundance of boron family in earths crust

A

Al>Ga>B>In=Tl

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24
Q

boron occur as

A

boric acid - H3PO3.
borax - Na2B4O7.10H2O
kernite - Na2B4O7.4H2O
colemnite -Ca2B6O11.5H2O

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25
Q

aluminum occur as

A

gibbsite- Al2O3.3H2O.
bauxite- Al2O3.2H2O.
diaspore-Al2O3.H2O.
corundum of alumina-Al2O3.

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26
Q

nature of corundum

A

hard and abrasive

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27
Q

all the trivalent compounds of grp 13 like BF3,AlCl3 are?

A

elecctron deficient(electron pair acceptor,lewis acid)-

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28
Q

if shielding effect in atom is highe then its size become

A

high

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29
Q

high shielding effect affects..

A

low ionisation energy,electronegativity,nuclear charge

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30
Q

order of shielding power?

A

s>p>d>f

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31
Q

Ga,In,Tl shows slight difference in properties when compares with boron and aluminium due to

A

due to weak shielding effect of d electrons

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32
Q

size of galium is lower than aluminium due to

A

weak shielding effect of d electrons present in galium

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33
Q

order of covalent radius

A

B<Ga<Al<In<TL

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34
Q

inert pair effect

A

inertness of valence s electrons to take part in chemical bonding

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35
Q

along a group inert pair effect..

A

increases

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36
Q

boron has has stable +3 effect due to

A

weak inert pair effect

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37
Q

thalium has stable +1 state due to

A

strong inert pair effect

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38
Q

order of stability in +3 state

A

B>Al>Ga>In>Tl

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39
Q

order of stability in +1 state

A

B<Al<Ga<In<Tl

40
Q

moving down a group lower oxn state become

A

more stable

41
Q

Tl3+ act as OA but Tl+1 do not act a RA

A

coz down the grp lower oxn state is more stable

42
Q

who can show +1 state among boron family

A

Ga,In,Tl

43
Q

Ga and In are more stable ine +3 than +1.true or false?

A

true

44
Q

Halides of Ga and In ______ in solution

A

disproportionate(3GaX—>GaX3+2Ga)

45
Q

TlX will not disproportionate due to

A

stable +1state

46
Q

thalium show some similarity in properties with alkali metals

A

due to +1 state

47
Q

thalium is called duckbill platipus why?

A

coz it shows the properties of other elements

48
Q

boron only forms covalent compounds but aluminium and other forms

A

both ionic and covalent compounds

49
Q

does an.Alcl3 forms covalent bond?

A

yes and it is non conducting

50
Q

an.alcl3 exist as

A

chlorobridged dimer

51
Q

structure of an.alcl3

A

monomer-sp2-trigonal planar
dimer-sp3-tetrahedral(inside angle=118 degree,inside bond length=206pm)(bondangle with another alcl3=79
and bondlength 221pm)

52
Q

wht abt hydrated alcl3

A

ionic and conducting(alcl3.6h2o)

53
Q

why boron halides do not forms dimer

A

boron is small it cant hold large sized halogen atoms

54
Q

why boron do not forms ionic compounds

A

bcoz the high values of first three ionsation enthalpies

55
Q

why alf3 is insoluble in an.HF and soluble in KF?

A

an.HF is highly covalent and hydogen bonded.hence it will not produce F^(-).but KF is highly ionic and easily release F^(-).

56
Q

why boron easily forms complexes than aluminium

A

due to small size and high electronegativity

57
Q

BF3 precipitates out AlF3 from soluble complexes ( like..)

A

Na3[Alf6]

58
Q

aluminium utensils should not be kept in water overnight.why?

A

aluminium reacts with water and dissolved oxygen to give a thin layer of al2o3 on surface.

59
Q

2Al + O2 +H2O –> Al2O3 + H2

A

little Al2O3 dissolves in water to form Al3+ wchich is injurius to health

60
Q

atomic radii of grp 13 elements is smaller than the corresponding group 2.why

A

due to increase of nuclear charge

61
Q

Ga has lower radius than aluminiumm

A

yah

62
Q

IE order

A

B>Tl>Ga>Al>In

63
Q

why thalium has a higher ionisation enthalpy than in indium?

A

in case of thalium increased nuclear charge by 32 units overweighs the shielding effect of HF and 5d electrons

64
Q

electronegativity decreases from boron to aluminium and then increases due to

A

weak shielding efffect of d anf f electrons

65
Q

EN values

A

B - 2.0
Al - 1.5
Ga -1.6
In - 1.7
Tl - 1.8

66
Q

boiling point decreases from boron to thalium due to

A

increase of size and hence decrease of interatomic interactions

67
Q

how melting point affects

A

decrease from boron to galium and then increases

68
Q

very low melting point for galium (30 deg).?

A

Ga 2 molecules are held by weak van der waals force

69
Q

neighbourhood of galium(solid) [existance of Ga2]

A

one cclose neighbour at a distance of 243pm and 6 more neighbours at 270-279pm

70
Q

why liq galium on solidification, volume increases upto 3%

A

in solid galium molecules are held by weak forces

71
Q

which are the 2 liq metals having melting point 30 deg

A

Ga,Cs

72
Q

density increases from boron to thalium

A

increase of mass overweighs the increase pf size

73
Q

when heated wirth air grp 13 elemts forms

A

trioxide or sesqui oxide(M2O3)

74
Q

oxide of boron is acidic.wht abt others

A

oxide of Al and Ga are amphoteric.
oxide of In and Tl are basic

75
Q

when boron and akuminium heated with aair forms

A

a mixture of both oxides and nitrides (b2O3,Al2O3)

76
Q

boron does not react with water or steam but

A

red hot boron reacr with cold water and forms oxide
2B+3H2O–>B2O3+3H2O

77
Q

aluminium react with cold water but ………. prevent further reaction

A

oxide layer

78
Q

gallium and indium will not reacct with water.Thalium react with….

A

moist air

4Tl+2H2O+O2–>4TlOH

79
Q

certain metals when dipped in c.HNO3 becomes incaative due to formation of protective oxide layer.those passive metals are

A

Fe,Cr,Al,Ni,co

80
Q

c.HNO3 can store in Al containers.why?

A

aluminium become passive with hno3

81
Q

boron doesnt react with non oxidising acids .wht abt others?

A

Al and others react with oxidsing and non oxidising acids by liberating hydrogen

82
Q

boron react with alkali (abv 773K) molten.wht abt others

A

being amphoteric galium and aluminiumreact with.aq. alkali by evolving H

83
Q

reactn with halogen

A

gives trihalide(except TlI3)

84
Q

halides of boron

A

BF3 - colourless gas
BCl3 - colourless liq
BBr3 - colourless liq
BI3 -white solid

85
Q

backbond has a …… chracter bcoz it results after the formation of sigma bond

A

pi bond

86
Q

boron halides are weak lewis acid.why?

A

electron deficiency of boron is compensated by ppi-ppi back bond

87
Q

BF3 is the weakest lewis acid

A

coz fluorine form strongest back bond due to small size high electron density

88
Q

order of acidic strength among trihalides

A

BF3<BCl3<BBr3<BI3

89
Q

stronger the backbond.weaker will be the lewis acid char.as size of boron fam increase lewis acid char decreases.

A

BCl3>AlCl3>GaCl3

90
Q

observed bond length of B-F in BF3

A

130pm (much less than sum of cov radii of B and F)

91
Q

bond order of BF3

A

tot.no.of bonds/ta.resonance=4/3=1.33

92
Q

during hydrolosis boron halides fumes in air due to

A

formation of hydrohalic acid (HCl)by hydrolisis

93
Q

BF3 will note fume in air.why?

A

it only undergo partial hydrolysis and form mixture of fluroboric acid (HBF4) and will not form HF.

94
Q

BF3 (lewis acid) combines with NH3 (lewis base) to give

A

1:1 addition prdt adducct

95
Q

hybridisation of BF3 and NH3 and its product

A

BF3–>sp2 hybridisation–>tirgonal planar

NH3—>sp3—>trigonal pyramid

product–>sp3 and tetrahedral

96
Q

anomalous behaviours of boron

A

1.boron is a non metal
2.boron exhibit allotropy but others not
3.boron has very high melting and boiling points than other
4.boron only forms covalent compounds
5.oxides and hydroxides of boron are acidic,but those of aluminium and galium-amphoteric,indium and thallium-basic.
6.hydrides of boron are highly stable but those of others are less stable.
7.boron reacts with active metals to give borides but others will not. Mg3B2

97
Q

diagonal relationship between boorn and silica

A

1.both are non metals
2.both cannot form higher form higher oxdn states and Si4+
3.both exist in amorphous and crystalline forms
4.both forms acidic oxides
5.both forms weak acid(boric acid,silicic acid)
6.both forms hydrides-boranes,slianes(B2H6,SiH4

inorganic chemistry (7 decks)

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