hi all! I am not able to understand what's
a Lewis acid and a Lewis base. tell me if
these are Lewis acids or Lewis bases and
tell me the reason. HCl, H2SO4, H3PO4,
CO2, HCN.
my approach: first 3 I'm not able to
decide. 4th one I thought to be Lewis
base as 2lone pairs of electrons left in
each oxygen atom. but I found
somewhere written that it's an acid. 5th
one is base as 1pair of electrons left in
nitrogen atom. please help. also tell me
the criteria to check if a compound is
electron deficient or has excess
electrons. also how to find the central
atom.
49thumb rule: the atoms with high electronegativity cannot donate the lone pair of electron in it!
H-C≡N has a lone pair on the N atom.. But it is very eletronegative. Thus cannot give it out its lone pair...
C-H bond is highly polar in nature.. thus can easily furnish H+ ions ..
Thus it is acidic in Arrhenius sense.. not lewis sense! :)
For a substance being a lewis base, the necessary condition is not that the substance should possess a lone pair but the substance should have a donateable lone pair of electron..
Hitesh deora gud..
1why is NH3 a Lewis base if nitrogen being highly electronegative cannot donate lone pair of electrons.
49P and S have vacant 3d orbitals in them so they can be treated as lewis acids too
none are lewis base coz even if there are lone pair present they are not donateable..
All are acidic...
49In NH3 the N is sp3 hybridised..
In H-C≡N, N has sp hybridisation..
in sp hybridisation, the s character is more...
In sp hybridisation there is 50% s character.. in sp3 the s character is 25%
And as we know the s orbital lies nearer to the nucleus, and so higher s character means the orbital is nearer to the nucleus and higher electronegative
Thus N in H-C≡N the electronegativity of N is higher than the electronegativity in NH3.
So NH3 can donate electron but not H-C≡N
1guess what? the first 3 aren't Lewis acids. not me but fiitjee package says that. I don't know why they have given this topic in class 10 without teaching hybridization. also tell me that if something isn't Lewis base then is it necessarily Lewis acid?
1you mean to say that every compound having P and S are Lewis acids?
49H2SO4 and H3PO4, i said, "can" be treated as lewis acids.. but I was not sure because they have ionisable H atoms and the acidity due to ionization of H is far more than that due to accepting lone pair..
Also there is large electron density on the 2 acids...
Thus maybe they repel incoming electron pair (not sure of ths reasoning though.. i will confirm later)
But first is NOT a lewis acid.. coz Cl has high density of electron on it.. so cant accept another pair! :)
1wow everything went over my head. this cannot be read without reading class 11th syllabus. I have phase test this Saturday and Sunday.
49Arey choro..! :P
Class 10 tests never matter! :P
this really is a class-11 topic!
SO peace maro!