# when lattice enthalpy becomes "less negative" what does it mean?Watch

#1
lattice enthalpy is the enthalpy change when 1 mole of gaseous ions form a solid compound right

and bond FORMATION is exothermic - it released energy
therefore lattice enthalpy is exothermic right ?

so if we say substance A has a "less negative" lattice enthalpy than substance B what does that mean?
does that mean less energy is released when its bonds are formed or does it mean more is releaseD?

Spoiler:
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also i understand that
if a substance has a "more exothermic" lattice enthalpy
then its because it has more attraction bewteen its ions but thats around it and i don't get why LE would be more exothermic because of that

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1 year ago
#2
(Original post by medhelp)
lattice enthalpy is the enthalpy change when 1 mole of gaseous ions form a solid compound right

and bond FORMATION is exothermic - it released energy
therefore lattice enthalpy is exothermic right ?

so if we say substance A has a "less negative" lattice enthalpy than substance B what does that mean?
does that mean less energy is released when its bonds are formed or does it mean more is releaseD?

Spoiler:
Show

also i understand that
if a substance has a "more exothermic" lattice enthalpy
then its because it has more attraction bewteen its ions but thats around it and i don't get why LE would be more exothermic because of that

If substance A has a less negative enthalpy than substance B, then substance A is the weaker of the two lattices. This is influenced by either the ionic radius or ionic charge.
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#3
(Original post by markschemes)
If substance A has a less negative enthalpy than substance B, then substance A is the weaker of the two lattices. This is influenced by either the ionic radius or ionic charge.
but how does having a less negative enthalpy indicate a weaker lattice?
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1 year ago
#4
(Original post by medhelp)
but how does having a less negative enthalpy indicate a weaker lattice?
I believe it's because it's closer to the theoretical value that's based on the perfect ionic model, which assumes lattices are perfectly spherical and have only ionic bonding, whereas the actual experimental values have slight covalent character and therefore have the stronger lattice and more negative lattice enthalpy (and vice versa).
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