Predict the following chemical formula for a compound between al and s.

You need to use the most common oxidation numbers for the two elements.

Al: 3+

S: 2-, 2+,4+and 6+ (2+ is rarer than 4+ and 6+).

Son you can predict a compound made up with Al 3+ and S 2-

=> Al2 S3 (remember that you exchange the oxidation numbers).

Al2 S3 is named aluminium sulfide and you can obtain it from this reaction of the elements:

2Al + 3S ---> Al2 S3

Al2 S3