Elements having octets


Moderators: Chem_Mod, Chem_Admin

Matt Sanruk 2H
Posts: 131
Joined: Wed Sep 18, 2019 12:21 am

Elements having octets

Postby Matt Sanruk 2H » Sun Oct 27, 2019 10:15 pm

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
Posts: 101
Joined: Fri Aug 30, 2019 12:18 am

Re: Elements having octets

Postby Jessica Booth 2F » Sun Oct 27, 2019 10:19 pm

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
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 435 times

Re: Elements having octets

Postby Chem_Mod » Sun Oct 27, 2019 10:21 pm

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
Posts: 52
Joined: Sat Aug 24, 2019 12:18 am

Re: Elements having octets

Postby Sarah Nichols 4C » Sun Oct 27, 2019 10:24 pm

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
Posts: 131
Joined: Wed Sep 18, 2019 12:21 am

Re: Elements having octets

Postby Matt Sanruk 2H » Sun Oct 27, 2019 11:13 pm

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?


Return to “Formal Charge and Oxidation Numbers”

Who is online

Users browsing this forum: No registered users and 2 guests