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2.1.3
Octet Rule
The octet

rule is a simple chemical
rule of thumb
Octet Rule says atoms with 8 electrons
in their outer shell are stable
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 nearest Nobel gas
The rule applies to the main-group

elements, especially carbon,
nitrogen, oxygen, the halogens, and
also to metals such as sodium or
magnesium.
In simple terms, molecules or ions
tend to be most stable when the
outermost electron shells of their
constituent atoms contain 8
electrons.
Noble Gases
group of elements were discovered at the end
of the 18th century
 They were un-reactive so they were called the
“Noble Gases”
 Later they were called “Inert Gases” as they did
not react and it sounded more scientific.
 Now called “Noble” again because they do
react under extreme conditions
 Atoms with a full outer shell of electrons are
very stable

Limitations
Doesn’t allow for
 H, He or Li
[stable with 2 e- in their outer shells] Duet Rule
 Transition elements - 18 electron rule
 BF3 which only has 6 e- in its outer
shell
How can atoms get a full outer
shell?
Give

away electrons
Take in electrons
Share electrons
Don’t bother getting a full outer
shell at all – (Rare but does
happen [BF3])
How can atoms get a full outer
shell?
Give

away electrons
Take in electrons
Share electrons
Don’t bother getting a full outer
shell at all – (Rare but does
happen [BF3])

More Related Content

2.1.3.1 octet rule

  • 2. The octet rule is a simple chemical rule of thumb Octet Rule says atoms with 8 electrons in their outer shell are stable 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 nearest Nobel gas
  • 3. The rule applies to the main-group elements, especially carbon, nitrogen, oxygen, the halogens, and also to metals such as sodium or magnesium. In simple terms, molecules or ions tend to be most stable when the outermost electron shells of their constituent atoms contain 8 electrons.
  • 4. Noble Gases group of elements were discovered at the end of the 18th century  They were un-reactive so they were called the “Noble Gases”  Later they were called “Inert Gases” as they did not react and it sounded more scientific.  Now called “Noble” again because they do react under extreme conditions  Atoms with a full outer shell of electrons are very stable 
  • 5. Limitations Doesn’t allow for  H, He or Li [stable with 2 e- in their outer shells] Duet Rule  Transition elements - 18 electron rule  BF3 which only has 6 e- in its outer shell
  • 6. How can atoms get a full outer shell? Give away electrons Take in electrons Share electrons Don’t bother getting a full outer shell at all – (Rare but does happen [BF3])
  • 7. How can atoms get a full outer shell? Give away electrons Take in electrons Share electrons Don’t bother getting a full outer shell at all – (Rare but does happen [BF3])