Smells Unit – Investigation II
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Transcript of Smells Unit – Investigation II
Smells Unit – Investigation II
Lesson 4:
Eight is Enough
© 2004 Key Curriculum Press.
Unit 2 • Investigation II
Admit Slip
• Draw the Lewis dot structure for the following covalently bonded molecule. Explain how you arrived at your answer.
Cl2 HBr NH3
© 2004 Key Curriculum Press.
Unit 2 • Investigation II
The Big Question
• How can we use Lewis dot structures to help draw structural formulas?
© 2004 Key Curriculum Press.
Unit 2 • Investigation II
Today’s Objectives:
• Students will be able to:
–Predict whether a given compound would be stable and likely to be found in nature.
© 2004 Key Curriculum Press.
Agenda
Admit Slip
Homework Check/Review
Notes
Classwork
Exit Slip
Product: Notes, Worksheet, Exit Slip
Homework: Back of Packet!
Unit 2 • Investigation II
© 2004 Key Curriculum Press.
Homework ReviewDraw structural formulas for the following molecular formulas.
1. C4H10O
2. C5H10O with one C-O double bond
Unit 2 • Investigation II
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3. C3H4O2 with two C-O double bonds
4. C4H9N with one C-N double bond
Unit 2 • Investigation II
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5.C3H5N with one C-N triple bond
Draw Lewis Dot symbols/ structures of:
6. Se 7. Br
Unit 2 • Investigation II
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8. As
9. CH4
10. H2O
Unit 2 • Investigation II
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Unit 2 • Investigation II
Cl Cl+ Cl Cl
Octet Rule 12 / 10 / 13
When bonding two atoms, 1 unpaired electron from each atom comes together with another unpaired electron to form a bond (2 shared electrons).
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• The octet rule states that atoms tend to form bonds by sharing valence electrons until eight (8) valence electrons surround each atom.…
…except for Hydrogen, H!
• Hydrogen will only have (2) valence electrons after it bonds.
• When the atoms have 8 (or 2) valence electrons, they are stable like the noble gases.
Unit 2 • Investigation II
© 2004 Key Curriculum Press.
Unit 2 • Investigation II
Activity
Purpose: In this lesson you will use Lewis dot structures to create structural formulas of molecules containing elements in addition to H, O, N, and C. You will look for patterns in the number of electrons surrounding each atom in a Lewis dot structure in order to develop further understanding of bonding.
(cont.)
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Unit 2 • Investigation II
Br2 H2S PH3 SiH4
1. Look at your drawings of Br2, H2S, PH3, and SiH4 above:a) How many electrons surround the Br atom on the left, including the ones it’s sharing?
b) How many electrons surround the Br atom on the right, including the ones it’s sharing?
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Unit 2 • Investigation II
c) How many electrons surround S, P, and Si?
d) How many electrons does each H have access to in these molecules?
2. How many chlorine atoms would bond covalently with a single carbon atom? Explain. (Hint: Use Lewis dot symbols to help you figure this out.)
3. Create a drawing representing the bonding of chlorine atoms with a single carbon atom. Start with the Lewis dot symbol for carbon.
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Unit 2 • Investigation II
4. How many fluorine atoms would bond covalently with a single phosphorus atom? Explain.
4. Create a drawing representing the bonding of fluorine atoms with a single phosophorus atom. Start with the Lewis dot structure of phosphorous.
4. Draw the structural formula of the molecule you created using Lewis dots symbols in question 5.
5. What is the molecular formula of the molecule you created in question 5?
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Unit 2 • Investigation II
CCl4 C+
Cl
Cl
Cl
Cl
P F+ 3 P
F
FF
P F
F
F
(cont.)
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Unit 2 • Investigation II
Making Sense
• The noble gases do not form bonds with other atoms (except under very extreme conditions). Explain why you think this might be true (use your Lewis dot structures).
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Unit 2 • Investigation II
Exit Slip
• Which of the following formulas satisfy the HONC 1234 rule?
• Which of the following formulas satisfy the octet rule?
• Which of the following formulas represents a stable compound we might find in the world around us?
a) CH3 b) CH4
© 2004 Key Curriculum Press.
Unit 2 • Investigation II
Wrap-Up
• Elements form bonds by sharing electrons until each atom has the same number of valence electrons as the noble gas in the same row of the periodic table — this is called the octet rule.