General principles of octet exception

[Ziyan Wang 3J]

What is the general principles of when we should conform octet rule and when not?

[Audrie Chan-3B]

P, S, and Cl can have expanded octets, but generally all the elements before it must abide by the octet rule.

[Jasmine Fendi 1D]

I think that everything in row 3+ can have an expanded octet, and elements such as Aluminum does not have to have an octet.

[Michelle Xie 2B]

Atoms with n=3 and greater can accommodate more than 8 electrons in its valence shell.

[andrewcj 2C]

The expanded octet comes from access to d orbitals, which can be used to create additional bonds to the 4 allowed by the s and p orbitals. In general, if an atom in a molecule can achieve a lower formal charge and make the molecule have a more logical formal charge by making more than 4 bonds (therefore violating the octet rule), it will.

[Anish Patel 4B]

Here is what I wrote down in my notes:
Less than 8 e-: H, B, He, Be (Aluminum and Boron only need 6 valence electrons)
More than 8 e-: P, S, Cl, Xe and below

[Sofia Barker 2C]

In general, H, He, and Li want 2 electrons because that satisfies the 1s orbital. Elements in period 3 and any period after can accommodate more than 8 valence electrons because of the d orbitals. Always check formal charge when drawing Lewis structures to confirm that the structure you have drawn is the most stable; this is the best way to prove whether or not the octet rule should apply or not.

[gabbymaraziti]

When a central atom has empty d-orbitals close in energy to valence orbitals, it can accommodate an expanded octet. Basically, atoms in the p-block of period 3+ can accommodate an expanded octet, but the size of the central atom also matters. It has to be physically capable of forming bonds to more extra atoms.