posted by Isabel .
I was wondering if somebody could help me with this...
Classify the following substances as covalent molecules or ionic compounds:
a. MgO e. LiCl
b. NI3 f. SF4
c. CuS g. XeF4
d. NO2 h. CsF
How do you know if they are covalent or ionic bonds?
Metal + nonmetal is usually ionic
Two nonmetals joined are usually covalent.
so CuS g. XeF4 would be ioninc right?
No. XeF4 is covalent, and CuS is ionic (to an extent).
To add to the excellent answer given to you by Bob Pursley, you may want to look in your text and read about electronegativity. That is a man-made scale that allows us to compare the ability of atoms to attract electrons. By taking the difference between the EN (electronegativity) of two elements, we can assign the degree of ionic or covalent character to the bond formed. Here is a site that will give you some more information. http://en.wikipedia.org/wiki/Electronegativity