ionic compounds are held together by electrostatic attraction, producing highly ordered crystals to reduce repulsion between similarly charged ions while maximizing attraction between oppositely charged ions. this explains the large energy required to break the bonds in ionic compounds.
metals are held together by metallic bonding (can't remember if you can use this phrase =P), which is the electromagnetic interaction between the delocalized electrons and metallic ions. this bonding however is nondirectional which explains why they are malleable and ductile. this explains why their lattice structure, although present, is weaker than in ionic compounds.
(long time since i touched chemistry, just what i remember =P just take this as a guideline to find the proper explanation in your notes and stuff)
Originally posted by Supaman92:Haha thanks! =D ionic bonds are non directional too rite?
They are strong and directional....
Hence if you are able to subject the compound to a force that's able to distort the lattice structure such that the like-charged ions face each other, the structure will shatter.
I think a better explanation will be using the formula:
Lattice energy is directly proportional to (q+ * q-)/(r+ + r-). As you might notice, ionic compound has q+ and q- while metal only got q+.
My bad....ionic bonds are non-directional....so sorry.
Originally posted by SBS2601D:
They are strong and directional....Hence if you are able to subject the compound to a force that's able to distort the lattice structure such that the like-charged ions face each other, the structure will shatter.
For such distortion to happen, all the bonds would have to be broken 1st and i would say its this distortion would shatter the structure even before the like charges will face each other.
Originally posted by dkcx:For such distortion to happen, all the bonds would have to be broken 1st and i would say its this distortion would shatter the structure even before the like charges will face each other.
is it?
What I was taught was that ionic particles are close together, so a sudden shock is sufficient to cause the layers to slip momentarily to bring the like charged ions together...
Originally posted by SBS2601D:
is it?What I was taught was that ionic particles are close together, so a sudden shock is sufficient to cause the layers to slip momentarily to bring the like charged ions together...
Not 100% sure since poly chem is more practical base and Uni doesn't really care about such things anymore.
To be able to move the ionic particles close together, the amount of energy required would be quite high and would the ionic bonds still be in effect in such a case or would they be momentarily broken i dunno.
Originally posted by Supaman92:Haha its okay =D so for my answer I just write that in metals the forces of attraction between the metal ions and the delocalised electrons are weaker than the forces of attraction between the oppositely charged ions in an ionic compound thus the value of LE is higher in ionic compounds than in metals la. Haha
Isn't that the question? Just that you paraphrased it...
Recall that in calcium, the calcium cations also have some repelling effect on one another due to "like charges repel" theory. Same goes for the electrons as well.
In calcium oxide however, the calcium cations and oxide anions are arranged in such a way that they maximise stability and minimise repulsion. The electrons do not have to be discussed in this case since they are localised.