[Rhubarb]

Hi there. I'm reviewing chemistry and I've come along a problem I can't seem to understand.

Now I understand that some transition metals and others like Sn or Fe have two possible charges. What I cannot figure out is the methodical way to determine the ionic charges of elements like Zn.

My first method I thought would work was to check the valence electrons. I checked the Periodic Table to see and found the "electrons in each energy level" numbers beside it. The numbers are (for Zinc) 2,8,18,2
I thought the third orbital has a capacity for 8 electrons like the second.
Is there a good trick for determining this like with A periods? 

Furthermore, should I just memorize elements that have several charges? 

Thanks for your time and patience with these questions.

[ajamil92]

Hi,

Many elements specifically trasition elements have exception in thier electron arrangement in thier shells. therefore it is not unusual for Zn to behave in that way. Now for metals with 1 charge type such as your example Zn, you can use the electronic configuration, if you know it...

Zn electonic configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 

However this way has some rules as to where electrons go first to which orbital, As you can see the 4th s-orbitals fills before the 3 d-orbital, but Zn will lose the 2 electrons in the s-orbital first, therefore will form a 2+ ion.

I suggest not using such a way with transition elements because it can get confusing, and when reaching the f-orbitals it can be difficult.

BUT what you can use alternatively, is that you can recall some of the compound Zn forms such as ZnO, therefore, since Oxygen needs 2 electrons, then Zn must provide 2 electrons, hence Zn forms the ion Zn2+.

Elements with several charges such as vanadium, you just have to memorise them, or remember the compounds it forms and find out the ion it forms with such a compund.

This is what i know, i hope it helped...