why PH5 does not exist

why PH5 does not exist


6 Answers

78 Points
11 years ago

Hi Shivam,

the extent of overlapping of d orbital of phosphorous and 1s orbital of hydrogen is very less because the energy difference between them is too high for favourable bond formation so that the most of 1s orbitals of 1s of hydrogens interact with p orbitals so that we can form PH3 but PH5 doesnt exists as d-s orbital overlapping is less and so it will dissociate into PH3 and H2.

priyanka tata

12 Points
7 years ago
The comment above this means that transition elements form unstable hydrides which is incorrect
19 Points
5 years ago
Since the phosrorus has its last electron in d orbital and hydrogen has the last electron in s orbital and since the energy difference in very high overlap doesn`t takes places in a good manners and so PH5 doesn`t.exist
Harshit Panwar
108 Points
5 years ago
It is one of the examples of the limitations of the octet rule I.e. expanded octet.
So, its not possible.
subhash sahu
21 Points
4 years ago
Although phosphorus exhibits +3 and +5 oxidation states, it cannot form PH5 . Beside some other considerations, high enthalpy of atomization value of dihydrogen and electron gain enthalpy of hydrogen do not favour to exhibit the highest oxidation state of phosphorus,and consequently the formation of PH5.
13 Points
4 years ago
In PH5 , forming H-P-H axial bonds, one p orbital of phosphorous and two 1s orbitals of both hydrogens should be involved in forming three molecular orbitals, but the difference in energy of 1s of H and 3p of P is large so LGOs of such combination would not form any bond.. 

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