Why would AlBr3 have single bonds between Br and Al. They can form double bonds to form an octet. Why do n't they form an octet?
Also, please do share exceptions regarding this concept so that I can remember them for my exam.
Hey! For elements such as Aluminum and Boron, we can say that they have an incomplete octet or they are electron deficient. What this means is that they can be stable with 6 electrons in total.
So for the example that you gave that says AlBr3, we can say that Aluminum will have 3 bonds around it, and 6 electrons present. Remember that these are the exceptions for the octet rule. We also have hydrogen as an exception to the rule, since it is stable with just 2 electrons. Beryllium is another exception to the rule since it is stable with 4 electrons. Hope that helped!