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chimanshu_007

some basic points in oxygen family

1)the acidic nature of the hydrides is quite reversed of wat is expected, bond is most polar in H2O , so it is least acidic

order is H2O < H2S < H2Se < H2Te

2)Only S , Se , Te in grp 16 shows catenation property (all 8 membered rings), Oxygen exist is diatomic , Po is monoatomic

3)H2O has the highest M Pt. and B Pt., this is due to extensive H-Bonding (though is contradictory by vander waal's forces)

4)FRrom 273 to 277K densityof water increases i.e it contracts , bt after 277K , it starts expanding with increase n temp so H20 has max density at 277K or 4 deg C

5) Rhombic sulphur melts at 387.5 K to a thin pale yellow liquid , bt at 453K , it suddenly becomes so viscous that it cannot be poured out frm the vessel

6)Electron affinities of 16 grp elements follows the order

O < S >Se >Te

this is due to small size of oxygen , as a result of small size , interatomic repulsions in 2p subshell of Oare more than in 3p subshell of S atom and S has large atomic size than O

some more pts

a) All elements of 16th grp exhibit -ive oxdn state except Polonium

b)the 1st 4 mmbers are named as calcogens means ore forming bcoz most of metal ores are oxides or sulphides

c)Po is naturally occuring radioactive element

d)Oxygen shows +ive oxdn state only in its compds with F2 coz F is more electro-ive than O

e)conc. HNO3 + concH2SO4 is called nitrating mixture or mixed acid

f)H2S is poisonous and antidote fr it is dilute chlorine

g)m pts and b pts of hydrides

H20 > H2S > H2Se > H2Te

Volatile nature

H20 < H2S < H2Se < H2Te

reducing character

H20 < H2S <H2Se < H2Te

bond angle dipole moment , thermal stability

H20 > H2S > H2Se > H2Te

not taken frm any site , i have posted wat i prepared frm my notes , u can find it in books , bt wich book that i can't say , so i collected them here fr u

hope u like it :)

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