Hi,

can you tell me what the valency of Aluminium and Selenium?

hi i was going to pose that question im glad you did are you doing s103 by any chance

Al is in group IIIA (or 3) depending upon the system you are using; therefore, it has three electrons in its outer shell, it will lose those three, to become a +3 ion. so the valence of Al is +3. Se is in group 16 (or VIA) and that means there are six electron in its outer shell. So it wants to gain two more to make eight and it has a valence of -2.

Excuse, please, but Al is in group IIIA or group 13 depending upon the system you are using.