Launch: 11/3   Grab your binder and immediately take a seat!

1.  Draw the correct Lewis symbols for the following atoms: i.  hydrogen ii.  neon iii.  nitrogen

iv.  bromine v.  strontium

Schedule   Monday (11/2): Covalent Bonds

  Tuesday (11/3): Covalent Bonds

  Wednesday (11/4): Covalent Bonds

  Thursday (11/5): Covalent Bonds

  Friday (11/6): Chemical Bonding Review

  Monday (11/9): Chemical Bonding Review

  Tuesday (11/10): Chemical Bonding Unit Exam!

Schedule   We don’t have time to waste!

  Follow our 6 class rules

  If you have a question, ask!   Ask your partner   Ask me

What are Lewis structures?

Mr. Heffner 11/3/09

Review: Octet Rule   Octet Rule:

  all atoms want to have 8 valence electrons   like the noble gases

Ne •  •  •  • 

•  •  •  • 

8 = 7 =

F •  •  •  • 

•  •  • 

Review: Covalent Bonding   To get 8, two nonmetals share electrons

F •  •  •  • 

•  •  •  F

•  •  •  • 

•  •  • 

7 = 7 =

Review: Covalent Bonding   To get 8, two nonmetals share electrons

F •  •  •  • 

•  •  •  F •  •  •  •  •  •  • 

8 = 8 =

Covalent Bond

What are Lewis structures?   Lewis structures are…

  used to represent covalent bonds between atoms

Ne •  •  •  •  • 

•  •  • 

Lewis Symbol

  Lewis structures are…   used to represent covalent bonds between atoms

F •  •  •  •  •  •  -

What are Lewis structures?

Lewis Structure

F •  •  •  • 

•  •  Covalent Bond

2 electrons = dash

What is a Lewis structure?   There is a 3-step process for creating Lewis

structures: 1.  Draw Lewis symbol for each atom and count dots 2.  Arrange atoms so they all have a full octet

  If more than 2 atoms, place first atom in center

3.  Count dots and convert shared pairs to bonds

Example Draw the Lewis structure for Cl2

  Step 1: Draw Lewis symbol for each atom and count dots

Cl •  •  •  • 

•  •  •  Cl

•  •  •  • 

•  •  •  14 dots

Example Draw the Lewis structure for Cl2

  Step 2: Arrange atoms so they have a full octet

Cl •  •  •  •  •  •  •  Cl

•  •  •  • 

•  •  •  8 = 8 =

Example Draw the Lewis symbol for Cl2

  Step 3: Count dots and convert shared pairs to dashes

Cl •  •  •  •  •  •  •  Cl

•  •  •  • 

•  •  •  14 dots

- Covalent Bond

2 electrons = dash

Example Draw the Lewis structure for NH3

  Step 1: Draw Lewis symbol for each atom and count dots

N •  •  • 

•  •  8 dots H

•  H •  H

• 

Draw the Lewis structure for NH3

  Step 2: Arrange atoms so they have a full octet   If more than two atoms, place first atom in center

N •  • 

•  •  •  H •  H • 

Example

H • 

8 = 2 =

H is an exception to the octet rule

H H

Draw the Lewis structure for NH3

  Step 2: Arrange atoms so they have a full octet   If more than two atoms, place first atom in center

N •  • 

•  •  •  H •  • 

Example

•  - - - 8 dots

Example Draw the Lewis structure for HCl

Whiteboards   Work in pairs

  Trade-off marker every question

  You have 60 seconds to draw the answer   Show all three steps!

  Lift board only when prompted

H2

Br2

SH2

CH4

Practice Questions   Practice Questions worksheet

Exit Slip 1.  In order to achieve a stable octet, two nonmetals

a.  form ionic bonds by transferring electrons. b.  form ionic bonds by sharing electrons.

c.  form covalent bonds by sharing electrons. d.  form metallic bonds by sharing electrons.

Exit Slip 2.  See whiteboard.

Exit Slip 3.  Which of the following correctly identifies the

Lewis structure for HF?

Exit Slip 4.  Bubble in A

Then, draw the Lewis structure for HI

Exit Slip 5.  Bubble in A

Then, draw the Lewis symbol for CBr4

Homework   Finish Lewis symbol and ions worksheet