Quick chem Q

Find out the # of valence electrons of those atoms first.

For example, S=6 need 2 more electrons Al=3 lose 3 electrons, when forming ionic bonds.
S2- + Al3+-->Al2S3

 

Yep that's easy.

It's all about valence electrons dude.

If you take a look at Aluminum on the Periodic table, you will see it's a Group IIIA element-- It has 3 valence electrons to give. And Sulphur is a Group VIA element-- It has 6 valence electrons (needs 2 more valence electrons to complete its outer shell).

So you need two Aluminums to give up a total of 6 valence electrons to complete the outer shells of 3 sulfurs.

So anytime you see a problem like that, look at the elements' groups on the periodic table, and think valence electrons!

Good luck!

edit: Whoa, bres there beat me to the "Post message" button by 60 seconds! I must be getting old..

 

Just wondering if you get the element chart on the dat?

that would be a hard question if you didn't get the chart. Otherwise you would have to remeber the charges, and who can remeber all the charges and #$$%

later hockey dentist

 

I would think that a standard reference source like the periodic table should be available on an exam if needed.

Shee-oot, it's been such a long time since I took the DATs I can't remember if I saw one in the tests..

 

The periodic table is available on the DAT.