Unit 5 Lesson 2 Lewis Electron Dot Diagram

Lewis Electron Dot Diagram

pen and paper model that shows the electrons in an atom or a molecule

• essential for determining the structure of molecules

Steps for Lewis Electron Dot Diagram for A Single Element

1. write the symbol for the element

2. place a dot for each valence electrons around the atom

3. alternate sides when placing the electrons(clockwise)

What’s the max amount of valence electrons in an atom?

8

How many orbitals are there to fill with electrons in a Lewis Electron Dot Diagram?

4

Dot Diagrams for Covalent Compounds(Regents)

1. Arrange the atoms(fewest valence electrons = center atom) using single bonds

2. Add remaining electrons as dots(work outside in)

3. Check everyone’s octet, if everyone is stable, you’re done; also check atoms and total # of electrons

4. Not enough electrons in your diagram?

   1. add a double or triple bond and check again

if possible, follow bond order rules and use electron expulsion theory and hund’s rule

Covalent Bonding Tricks

1. Hydrogen only makes single bonds because of its duet, never goes in the middle, and has no lone pairs

2. Group 17 only makes single bonds and never goes in the middle(6 lone pairs of electrons)

3. Group 16 likes to make double bonds, but can make single

4. Group 15 likes to make triple bonds, but can make double and single

5. Carbon always goes in the middle if it’s there

6. Least electronegative element goes in the middle

Polyatomic Ions

an ion that contains more than one atom has net charge when the total group has either gained or lost an electron

How to Draw Diagrams for Polyatomic Ions

1. add charge in the upper right hand corner of the diagram

2. add extra electron to total if -, subtract if +

Ionic Compound Diagrams Rules

for cations:

• symbol and positive charge

• no dots(metals lose their valence electrons)

for anions:

• symbol and negative charge

• 8 dots(nonmetals gain enough electrons to complete the octet)

other:

• arrange the ions however you want

• no dashes between them

If there are multiple possible charges,

let the multiple molecules cancel out