[illusionme]

1)explain in terms of structure and nature of ions why the melting poiint of copper(II)oxide is higher than that of sodium chloride

2) what's the oxidation state of chlorine NaClO₃? how do i calculate this qn?

[freezard7734]

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1)explain in terms of structure and nature of ions why the melting poiint of copper(II)oxide is higher than that of sodium chloride

2) what's the oxidation state of chlorine NaClO3? how do i calculate this qn?

1)Note that coulomb potential is proportional to the magnitude of the charges of both ions. Therefore, since copper(II) oxide is [Cu2+][O2-] and sodium chloride is [Na+][Cl-], copper oxide will have more potential energy; thus, it will take more energy to melt CuO

2)The formal definition of oxidation number of a specie is the number bonds where itself is the more electronegative minus the number of bonds where itself is the less electronegative.
But a good rule of thumb is: Alkali metals are always +1, and oxygen is almost always -2. And the oxidation numbers of each species always adds up to the charge of the total compound charge.