11 2 what is a lewis symbol

Launch: 11/2   Grab your binder and find your new seat

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Launch: 11/2   Ask your partner:

1.  What is your name? 2.  What did you do for Halloween?

3.  What is one thing in Chem that you really understand? 4.  What is one concept in Chem that you struggle with?

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

Human Bonding   Take out a new sheet of paper

  Crunch it up into a ball

  When instructed, stand up and walk around class   Push in your chair

  When the music stops, form a bond!   Ionic – exchange electron   Covalent – share electron

What is a Lewis symbol? Mr. Heffner 11/2/09

What is a Lewis symbol?   Lewis symbols are…

  used to represent atoms in covalent bonding

Ne Gilbert N. Lewis

•  •  •  • 

•  •  •  • 

Lewis Symbol

What is a Lewis symbol?   Two pieces of information

  The element   Ne = Neon

  The number of valence electrons   8 dots = 8 valence electrons

Ne •  •  •  • 

•  •  •  • 

Dot = 1 valence electron

Element’s symbol

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

symbols: 1.  Place element’s symbol in center 2.  # of valence electrons? 3.  Place electrons around symbol

Example Draw the Lewis symbol for hydrogen.

  Step 1: Place element’s symbol in center

H

Example Draw the Lewis symbol for hydrogen.

  Step 2: # of valence electrons?

Example Draw the Lewis symbol for hydrogen.

  Step 2: # of valence electrons?

“The Trick”: Group #

group # = 1 # valence electrons = 1

Example Draw the Lewis symbol for hydrogen.

  Step 3: Place electrons around symbol

H • 

Example Draw the Lewis symbol for carbon.

  Step 1: Place element’s symbol in center

C

Example Draw the Lewis symbol for carbon.

  Step 2: # of valence electrons?

Example Draw the Lewis symbol for carbon.

  Step 2: # of valence electrons?

“The Trick”: Group # Drop the 1!

group # = 14 # valence electrons = 4

Example Draw the Lewis symbol for carbon.

  Step 3: Place electrons around symbol   One on each of the 4 sides   No doubling up!

C •  •  • 

• 

Example Draw the Lewis symbol for sulfur.

  Step 1: Place element’s symbol in center

S

Example Draw the Lewis symbol for carbon.

  Step 2: # of valence electrons?

Example Draw the Lewis symbol for sulfur.

  Step 2: # of valence electrons?

“The Trick”: Group # Drop the 1!

group # = 16 # valence electrons = 6

Example Draw the Lewis symbol for sulfur.

  Step 3: Place electrons around symbol   One on each of the 4 sides   Double up after all sides have at least one

S •  •  • 

•  •  • 

Practice Questions 1.  Draw the Lewis symbols for:

i.  Nitrogen ii.  Fluorine

iii.  Phosphorus iv.  Xenon v.  Calcium

vi.  Iodine vii. Magnesium

viii. Arsenic ix.  Sodium x.  Silicon

Exit Slip 1.  Unlike in ionic compounds, atoms in covalent

compounds a.  share valence electrons to obtain a stable octet. b.  are always a nonmetal and a metal. c.  exchange valence electrons and form ions.

d.  are always two metals.

Exit Slip 2.  How many valence electrons does chlorine (Cl)

have? a.  17 b.  8 c.  2

d.  7

Exit Slip 3.  Which of the following is the correct Lewis symbol

for oxygen?

Exit Slip 4.  Bubble in A

Then, draw the Lewis symbol for iodine.

Exit Slip 5.  Bubble in A

Then, draw the Lewis symbol for magnesium.

Homework   Finish Lewis symbol and ions worksheet