LEWIS DOT DIAGRAMS
Drawing Covalent Compounds
Drawing Dot DiagramsA dot diagram shows the valence electrons for an atom
First, write the symbol for the element.
Drawing Dot DiagramsThen, put a dot to show each electron in the outer shell, in the following order:
X 36
4758
1 2
• The first two spots for electrons represent the s sublevel
• the last three sides represent the three orbitals of the p sublevel.
Drawing Dot DiagramsDrawing Dot Diagrams
Two Exceptions
Carbon and silicon are exceptions to the pattern
Two exceptions:Carbon and silicon have hybrid orbitals, so their dot diagrams will look like this: C
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An Addendum to Lewis StructuresHybrid orbitals: the s and p sublevels blend together and have four equal energy
Nitrogen
sulfur
silicon
chlorine
Covalent BondingA covalent bond occurs when two nonmetals share electrons.
Covalent Bonding (Review)◦Octet Rule◦ In forming covalent bonds, electron sharing usually occurs
so that atoms can have 8 electrons◦H, Li, Be, and B are exceptions to this…they only want two
Lewis Dot StructuresOR Covalent Bonding Diagram◦Lewis Dot Structure : The structures of molecular compounds can ◦Covalent bonds are shown using dashes◦Dashes represent TWO electrons
Single Covalent BondSingle bond: Sharing a single pair (two) of electrons
Single covalent bond
Multiple Bonds◦Double bond : sharing two pairs (four) of electrons◦Triple bond : sharing three pairs (6) of electrons
◦Multiple covalent bonds usually occur in atoms that conatin carbon, nitrogen, and oxygen
Unshared Pairlone pair A pair of valence electrons THAT DOES NOT BOND
Lone pair
Each fluorine atom has 3 lone pairs
Drawing Lewis Structures◦I am going to go through the steps of drawing lewis structures, the steps are also written on the board. ◦There are 6 steps
Drawing Lewis Structures for Covalent Compounds
1. Determine the total # of valence electrons for all atoms
2. Draw the electron dot structures for all the elements
3. Choose the center atom-The least lone pairs- Carbon is always the center-Hydrogen is never the center
4. Place the outside atoms around the center and indicate a shaired pair with a dash
5. All atoms must have 8 electrons around then (except for H)
5. Make sure your covalent bond structure has the same number of electrons as you calculated
H2O
CCl4
CO2
HCN
PCl3
CSF2
Some molecules have multiple center atoms or none
Draw the electron dot structure to figure out how they will bond
C2H4
H2O2
O2
H2
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