# enthalpy

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#1
is bond enthalpy equal to the amount of energy in the bond? I am confused as to why we can calculate change by enthalpy of reactants-enthalpy of products

I understand energy required to break the bonds-energy required when bonds form. but is the energy released when new bonds form equal to the energy required to break the bonds and therefore the amount of energy in the bond?
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1 year ago
#2
(Original post by utv)
Is the energy released when new bonds form equal to the energy required to break the bonds?
equal in magnitude, but opposite in sign
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#3
thanks for your help so much. I can't leave a rep as I've reped you lots and it won't allow me. I really appreciate it.

is it to do with electrons in orbitals and their energy levels? why the magnitude is equal?
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1 year ago
#4
(Original post by utv)
thanks for your help so much. I can't leave a rep as I've reped you lots and it won't allow me. I really appreciate it.

is it to do with electrons in orbitals and their energy levels? why the magnitude is equal?
All bonds are electrostatic in nature, so it does involve the electrons.

Have you heard of a potential energy well?

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#5
I'm in year 12 so no we havent learnt it but I have a really tough understanding

is it to do with the bonding pair being at a low energy level . but when atoms are formed due bonds absorbing energy electrons are at a high energy level

when energy is released when bonds form, electrons go from a high energy level to a lower energy level(the energy level of the bonding pair) and when this happens energy eg UV light is released?
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1 year ago
#6
(Original post by utv)
I'm in year 12 so no we havent learnt it but I have a really tough understanding

is it to do with the bonding pair being at a low energy level . but when atoms are formed due bonds absorbing energy electrons are at a high energy level

when energy is released when bonds form, electrons go from a high energy level to a lower energy level(the energy level of the bonding pair) and when this happens energy eg UV light is released?
Molecular orbital model
The electrons occupy a molecular orbital, which is at lower energy than the atomic orbitals that they occupied before bonding.

The above is a model, which explains empirical observations.

However, as I have already said, bonding is fundamentally electrostatic interactions between electrons and the nuclei of the bonded atoms. The atoms occupy a position at which the attractions are maximised and the repulsions minimised.

The whole thing is at lower potential energy than before (potential energy well).
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#7
great thank you very much
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