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Inorganic Chemistry

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28 Jan 2009 00:40:03 IST

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Why is N2 a gas while P4 a solid?

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Why is N2 a gas while P4 a solid?

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Debotosh Chatterjee

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28 Jan 2009 10:15:59 IST

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will be posting the solution soon................i have to go offline now for urgent reasons!!!!!!!!!

10904him

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28 Jan 2009 10:30:56 IST

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N2 has lesser molecular wt while P4 has high mol wt.

JPS

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28 Jan 2009 12:15:50 IST

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N2 exista as a dimer by virtue of multiple bonds and the N2 molecules are held together by weak van der waals forces. It cannot have single bonds due to low bond dissociation enthalpy of N-N which is a consequence of lp-lp repulsion (it is more in case of N bcoz of its small size). whereas P4 cannot have multiple bond due to large and diffused orbitals as a result of which they cant have effective overlapping. so, P4 exists withP-P bonds and it is polymeric i.e. the intermolecular forces between them is covalent bond which is much stronger than vdw forces. so N2 is a gas while P4 is a solid.

Debotosh Chatterjee

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29 Jan 2009 08:29:02 IST

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nirogen molecule is diatomic. due to smaller size of N-atom , its valence shell electrons can undergo sidewise overlap and as a result 2 pie bonds are formed between two N-atoms. thus the two N-atoms are linked to each other by one sigma and 2 pie bonds . the discrete nitrogen molecules are held together by weak vander waals forces . on the other hand , as the size of the P atom is bigger, sidewise overlap between 2 P atoms is not possible and hence multiple bonds are not formed between two P atoms. as a result phosphorus molecules consist of 4-P-atoms . the 4-P atoms in the molecule are arranged at the four corners of a tetrahedron and linked to each other by a single covalent bond . as the molecular mass of N₂ is much less than that of P₄ the force acting between the nitrogen molecules is much less than the force acting between the phosphorus molecules . thus the vanderwaals forces in the phosphorus molecules is much more than that between nitrogen molecules ...............HENCE PHOSPHORUS IS A SOLID WHEREAS NITROGEN IS A GAS AT ROOM TEMPERATURE!!!!!!!!!!!

rafa in revival mode

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29 Jan 2009 08:51:17 IST

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n n triple bond is very stable bcoz of greater strength and high bond dissociation energy of n nbond.so they cant catenate like carbon .so they are holded by \weak vander wall forces.p4 is a solid because it is bonded by single bonds and by covalent forces of attraction.

rafa in revival mode

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29 Jan 2009 08:52:51 IST

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i want to ask jps how n2 exists as a dimer

JPS

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29 Jan 2009 11:59:54 IST

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sorry i mean to say that nitrogen exists as a diatomic molecule. its not a dimer .really sorry for language problem.

SAURABH SHARMA

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29 Jan 2009 12:14:30 IST

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it is due to stronger d pi-d pi bonds in phosphorous as compared to p pi-p pi bonds in nitrogen moreover there is an increase in van-der-waal's forces

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