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## Summary:

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Drago rule states that if –

Drago's rule was introduced to explain why the bond angles of molecules such as ##PH_3##, ##AsH_3##, ##SbH_3## differ so much from ##109^o28'## which is supposed to be the ideal bond angle of molecules with ##sp^3## hybridization(as the steric number ##Z = 4##). Is the fact that Dragos rule exists prove somewhat the failure of hybridization theory as the theory itself predicts the bond angles to be ##109^o28'## but in actuality, the bond angles are closer to ##90^o## hence implying hybridization does not take place?

The theory of hybridization does not account for the bond angles of these elements to be (##\approx 90^o##) and Dragos rule was born out of only experimental data.

The only theoretical proof that I have found that predicts Dragos rule is

(https://madoverchemistry.com/2018/1...l-bonding-24-covalent-bonding23-drago-rule-2/)

I am unclear as to how they get those equations(I can't find post 69 but I suspect its an equation from orbital analysis but I am not too sure) here it is proving by contradiction that no hybridization is going to take place in phosphine(##PH_3##) instead of solely relying on experimental data.

so in short I don't understand:

1. the theoretical prediction of Dragos rule(which is given in the link above) using orbital analysis.

2. If the fact that Dragos rule exists proves the failure of hybridization theory.

- the central atom has at least one lone pair of electron on it
- the central atom belongs to group 13,14,15 or 16 and is from the 3rd to 7th period.
- if electronegativity of the central element is 2.5 or less
- no. of sigma bonds+ lone pair=4

Drago's rule was introduced to explain why the bond angles of molecules such as ##PH_3##, ##AsH_3##, ##SbH_3## differ so much from ##109^o28'## which is supposed to be the ideal bond angle of molecules with ##sp^3## hybridization(as the steric number ##Z = 4##). Is the fact that Dragos rule exists prove somewhat the failure of hybridization theory as the theory itself predicts the bond angles to be ##109^o28'## but in actuality, the bond angles are closer to ##90^o## hence implying hybridization does not take place?

The theory of hybridization does not account for the bond angles of these elements to be (##\approx 90^o##) and Dragos rule was born out of only experimental data.

The only theoretical proof that I have found that predicts Dragos rule is

(https://madoverchemistry.com/2018/1...l-bonding-24-covalent-bonding23-drago-rule-2/)

I am unclear as to how they get those equations(I can't find post 69 but I suspect its an equation from orbital analysis but I am not too sure) here it is proving by contradiction that no hybridization is going to take place in phosphine(##PH_3##) instead of solely relying on experimental data.

so in short I don't understand:

1. the theoretical prediction of Dragos rule(which is given in the link above) using orbital analysis.

2. If the fact that Dragos rule exists proves the failure of hybridization theory.

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