classic chem if i wanted to bond, could i? 9-12 science std: chem 2a
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Classic Chem
If I wanted to bond, could I?
9-12 Science Std: Chem 2a
Previously, on “Chem is Fun”Review from beginning:
Started with Atom
The parts
The electrical charges
The orbitals
Valence Electrons
Previously, on “Chem is Fun”Review from beginning:
Valence electrons
Outer shell…
Electrons that bond….
electron
neutron
proton
Previously, on “Chem is Fun”Review from beginning: How many there are….
Working with table…
Count from left…
3 4 5 6 7 81 2
Or look at column number
Previously, on “Chem is Fun”Review from beginning:
Sharing electrons
Covalent, Polar Covalent and Metallic
Previously, on “Chem is Fun”Review from beginning:
Taking / Giving Electrons
Ionic Bonds held by Electrostatic Forces
Not all atoms can bond It depends on the number of valence electrons
Imagine if you will…..
This building has 8 apartments / floor
…..An apartment building
“Eight is Great”
Not all atoms can bond Each floor of the apartment is an element or atom
The Number of full or empty “apartments”….
…is important to the “landlord” atom
Valence electrons live in
the apartments….
Not all atoms can bond When atoms bond…
Atoms work together to move electrons
So that each atom has either…
…an empty or full floor
from “apartment” to “apartment”
Not all atoms can bond When atoms bond…
If they can’t fill or empty a floor
The atoms don’t want to bond
Here’s how it works….An atom with 2 valence electrons
Wants to Bond with an atom with 6 valence electrons
Atoms aren’t happy – floors aren’t empty or full
Here’s how it works….This atom takes its electrons
And moves them to the other atom
Now both atoms are happy and can bond
Here’s how it works….This is called the “rule of eight”
Or the “Octet Rule”
Remember – “Eight is Great”
Here’s how it works….If the atom can’t fill or empty the floor…
The Octet Rule isn’t followed…
And the atoms don’t want to bond
Here’s an exampleAn atom with 3 valence electrons
Comes near an atom with 5 valence electrons
Will these atoms bond?
Here’s an exampleThis atom moves its 3 electrons
Into the 3 empty places in this atom
And the atoms will get together and bond
Yes!
Another example:An atom with 2 valence electrons
Sees an atom with 5 valence electrons
Will these atoms bond?
How could they bond?Move the electrons and this atom is happy…
Where could they get it?
But this atom still needs one for the Octet Rule
A 3rd Atom with one electron
Bonds with more than 2 atomsYou bring in a 3rd atom with 1 valence electron
And both atoms move their electrons
Now all 3 atoms have met the Octet Rule
And all 3 atoms will bond together!
Does this work the other way?Will an atom with 5 valence electrons
Move those 5 to an atom with only 3?
It is easier to move 3 electrons than 5
No – 3 electrons will move to the atom with 5
How about this one…You have an atom with 4 valence electrons..
It wants to meet the Octet Rule to be happy
So it looks for atoms to bond with
How about this one…It sees 2 other atoms with 2 valence electrons
Will it bond with these 2 atoms?
Yes!
The 2 electrons from the new atoms will move to the atom with 4
The Octet Rule is satisfied for all 3 atoms!
How do you figure out how manyYou have an atom with 6 valence electrons…
And an atom with 1 valence electron
Will 1 of each atom bond?
No – they don’t meet the Octet Rule
How do you figure out how manyWhat is needed to meet the Octet Rule?
I need 1 more atom with 1 valence
electron
Then they have all 8 (or no) valence electrons…
And all 3 will bond together
One more situation…You have an atom with 8 valence electrons
It sees atoms with 1 and 2 valence electrons
Will the atoms bond?
No!
One more situation…The first atom has 8 valence electrons
It already meets the Octet Rule
The other 2 atoms don’t have enough to either fully fill or empty their 8
So they won’t bond
One more situation…What group of atoms have 8 valence electrons?
The Noble Gases (group 18)
Because these atoms have all 8 valence electrons…
They don’t bond (react) with other atoms
One more situation…
That is why the Noble Gases don’t react
They are monatomic atoms
The hermits of the Periodic Table
So now it is time for practice
You have a worksheet in front of you….
So now it is time for practiceKnowing what you know about the Octet Rule…
Fill in columns 2, 4, 5 and 6 of this table
So now it is time for practiceKnowing what you know about the Octet Rule…
For extra credit, fill in the information in Column 7 (see example)
Your Homework…..
Finish your Octet Rule Worksheet
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