What is atoms need to do to obey the octet rule?

Answer 1

Fine question. And a hard one.

Let's step back a second and appreciate that the octet rule is indeed a rule, not a law. It isn't always followed. In fact it's really only applicable to first row elements...but that's fine because they're used a LOT.

Secondly, it's just a rule we use to simplify thousands of experimental observations and trends into something that is easy to use. As with a lot of chemistry (so, so much of chemistry!) it's a slightly inaccurate imaginary device to make our lives easier.

That said, there's no reason we can't come up with some intuition. So, why 8?

Well, when we reach our octet we become fairly inert...like a noble gas (which naturally has it's octet filled). It's easy to see that gaining any more electrons is going to be difficult, you're starting a new - much higher energy - shell. It's not impossible but it's unlikely, so you're stable at 8 in that respect.

That's easy to see. But why can't we lose electrons? Well if a noble gas loses one, the charge is unbalanced. It's hard to remove an electron like that, we can see. But why don't we get Nitrogen kicking around on it's own with 3 unpaired valance electrons?

This kind of ties into the next question -why try to get to the octet in the first place?

Well, for one, it's nice to bond. When you bond, energy is released...meaning the atoms are in a lower energy state than before. Lower energy = more stable. Mostly because electrons want to be close to protons...even protons of other atoms. Pairing up with another electron to do this isn't the best thing in the world, but it's worth the minor electron-electron repulsion to get a nice big electron-proton attraction.

So if we bond as many things as we can until we reach 8 electrons (at which point more bonds = filling more shells = higher energy = unstable...so we don't pass 8) then we can lower our energy as much as possible, and that's a good thing.

And that's a good outlook to have on it. We see why a lone atom strives to bond and then we also see why it stops bonding when it gets to 8 valance electrons. I'm sure you could think of different little reasons all day. But we're explaining a general trend here.

Hope that helps.

Answer 2

The octet rule is a simple rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electron configuration as a noble gas. The rule is applicable to the main-group elements. In simple terms, molecules or ions tend to be most stable when the outermost electron shells of their constituent atoms contain eight electrons.

Answer 3

Atoms need to obey the octet rule, because if they do, they will become stable. To become stable, they need 8 valence electrons (electrons on the last electron shelf/cloud). Only the noble gases (on the right side of the Periodic Table) have the total amount, and so they are stable.

Answer 4

to be more like a noble gas and be less reactive. having the same number of electrons as a noble gas makes the atom more stable.

Answer 5

the octet rule applies to atoms that have less than 20 electrons <20