CHEMISTRY COMMUNITY

What are the general exceptions to the octet rule we should know? And how many electrons can those exceptions hold when bonding?

The 3rd row and beyond can have expanded octet, more than 8 electrons. H, He, Li, Be will always have an incomplete octet. The 13th column or the Boron column can have an incomplete octet.

I don't think there is a specific number of electrons that each expanded octet can hold that we need to know, just know that it is more than 8

Anything in period 3 or larger can have a expanded shell because electrons can fill the D orbital

Hydrogen, Helium, and Lithium will follow a duet rule. This is because their electrons are present the 1s orbital, which is most stable when full (2 electrons). Hydrogen thus wants to gain an electron while Lithium wants to lose an electron in order to have the most stable electron configuration, which is that of Helium.

Not an exception to the octet rule, but to the typical electron configuration pattern - chromium and copper. They're [Ar]3d⁵4s¹ and [Ar]3d¹⁰4s¹ respectively, you just have to know that a half-filled or full d is more stable than a full s subshell.

The third row of the periodic table and beyond can have expanded octets as they have the d orbital available and are also larger atoms.

Anything from the third row the periodic table and the rows that follow can have expanded octets.