Chemistry homework...

How does the ionic bonding model explain the relatively high melting points of ionic compounds; how does the model explain the non-conductivity of ionic solids and at the same time the conductivity of ionic solutions?


...what is the ionic bonding model?

How does the Lewis bonding model explain why certain combinations of atoms bonding covalently are stable while others are not?

How does the Lewis model for covalent bonding explain the relatively low melting and boiling points of molecular compounds?

...?

 

alrighty

high melting pints of ionic compounds:

Because of the nature of ionic bonding, ionic compounds have very strong electrostatic attraction between their anions and cations. It takes lots of energy to break these atoms apart and hence why their melting points are generally very high. factors that effect their melting points are the strength of the electrostatic attraction eg a 2+ cation with a 2- anion is stronger then a 1+ and 1- because there are 2 electrons taking part in ionic bonding rather then 1. Also the size of the particles involved, smaller ions result in them packing together tighter increasing the melting point.

Conductivity:

electrical conductivity is determined by a compunds mobile free particles (ions) capable of carrying a a charge. since ionic solids form a tightly bound lattice network their conductivity is low due to their particles being held together tightly and not being able to move electrically through a circuit.

In the case of ionic solutions we now have free anions and cations capable of moving through a circuit and carrying their electrical charge through as well. anions are negatively charged and hence will move toward the negative electrode. cations are positive and move to the positive electrode. Thus ionic solutions are much more capable of carrying an electrical charge then ionic solids.

the model? you can figure that out, or google it ;~)


How does the Lewis bonding model explain why certain combinations of atoms bonding covalently are stable while others are not?

(you mean the lewis dot diagrams right?)

because it shows the interactions of valance electrons between atoms, for example you are able to see if lone pairs are having an effect on a bond causing repulsion of other atoms and a lower stability, also the stability can be judged on whether the bonding interactions between two compounds will cause them to receive full outer shells from their interactions also providing predictive power of the new compounds stability.

How does the Lewis model for covalent bonding explain the relatively low melting and boiling points of molecular compounds?

hmm not too sure about this one, im sure if you looked around on google and had a read you would be able to figure it out lemme know if you have any more questions!