Elements having octets

[Matt Sanruk 2H]

I am still slightly confused on how some elements can over an octet, while we also automatically assume some elements have octets no matter what. Can someone clarify for me?

[Jessica Booth 2F]

C,N,O,F always form an octect and anything with an atomic number above F has a d-shell, so they can form expanded octects.

[Chem_Mod]

The most common exception to the octet rule is a molecule or ion with with at least one atom that possesses more than an octet of electrons. These compounds are found for elements of period 3 and beyond. For example, sulfur can accommodate more than eight valence electrons by using one or more d orbitals. Sulfur and oxygen are the most common elements seen to exceed the octet rule and have an expanded valence shell.

[Sarah Nichols 4C]

The octet (8 e-) comes from the full s- and p- subshells; s2p6 totals 8 electrons. Atoms in period 3 or higher have valence shell d-orbitals, so they can accommodate more electrons than the standard 8 for atoms with lower atomic numbers

[Matt Sanruk 2H]

Okay, so CNOF are always octets since they do not have a d orbital, but those that have d orbitals (periods 3+) can have more if their formal charge allows for it?