Textbook Problem 2.A.15

[805377003]

Can someone explain this problem?

Write the most likely charge for the ions formed by each of the following elements: (a) S; (b) Te; (c) Rb; (d) Ga; (e) Cd.

[Becca Nelson 3F]

We can look at trends in the periodic table to determine what charge ion an element is most likely to form.
a)Sulfur is group 16, so it is most likely to have a charge of -2
b)Tellurium is also group 16 so it will likely have a charge of -2
c)Rubidium is group 1 so it will most likely have a charge of +1
d)Gallium is a Group 13 element, so it is most likely to have a charge of +3
e)Cadmium is a transition metal, but it most often has a charge of +2
In order to determine the charge on an ion, consider what the element has to do to have a similar configuration to a noble gas. For me, I like to look at the groups and pick an element in the group that I know the charge of, and often the other elements in that group have the same charge. I know Aluminum is +3, so when I saw gallium in the same group, I knew it should be similar.

[Simrah_Ahmed1J]

Yes, you have to look at the ions and see whether a positive charge (losing an electron) or a negative charge (gaining an electron) would be most 'advantageous' in acquiring a full orbital.

But I see how it could be confusing for some elements because like, for example, in the case of Carbon, it is technically able to get a full energy level by having a 4+ charge or a 4- charge, but I'm not sure if we really even have to worry about confusing cases like that.

Also another thing, this doesn't actually give you a good way to logically figure out whether the charge an atom might have, but I guess if you're working on a problem and there is a specific atom you are not really sure about what charge it might have because its not so obvious if it 'wants' to lose electrons and go to a full lower energy level, or gain electrons and complete the current energy level, or it wants to be half full or whatever the case, to confirm what your thinking might be true you can look up "common charges of (whatever element)" and then check what you find against the answer you were thinking of.