Launch: 11/5   Grab your binder and immediately take a seat!

  Place homework (practice questions) on desk

1.  Draw the correct Lewis structures for the following atoms. Be sure to use the 3-steps!

i.  HI

ii.  PH3 iii.  O2

Schedule   We have an exam in 5 days!

  We don’t have time to waste!   Follow our 7 class rules

  You may not use inappropriate language

  If you have a question, ask!

What are the two types of covalent bonds?

Mr. Heffner 11/5/09

What are the two types of covalent bonds?

  The two types of covalent bonds are… 1.  Non-polar covalent bonds:

  Electrons are equally shared

H •  H • 

Shared in the middle

What are polar bonds?   The two types of covalent bonds are…

2.  Polar covalent bonds:   Electrons are unequally shared

H •  Cl

•  •  •  • 

•  •  •  Closer to Cl, but still

shared!

Why are electrons shared unequally?

  Electrons are shared unequally because..   of differences in electronegativity

  electronegativity = how strong (and greedy) atoms are

Why are electrons shared unequally?

Non-polar covalent

Polar covalent

.5 1.7

Shared equally

Shared unequally

Ionic

Ripped off (transferred)

Why are electrons shared unequally?

  There is a 3-step method for determining whether a bond will be

Example #1 Is H – H a nonpolar covalent or polar covalent bond?

  Step 1: Find electronegativity   H = 2.1   H = 2.1

Example #1 Is H2 a nonpolar covalent or polar covalent bond?

  Step 2: Subtract electronegativities   2.1 – 2.1 = 0

Example #1 Is H2 a nonpolar covalent or polar covalent bond?

  Step 3: check number line   0 is less than .5

Non-polar covalent

Polar covalent

.5 1.7

Ionic

Example #2 Is HCl a nonpolar or polar covalent bond?

  Step 1: Find electronegativity   H = 2.1   Cl = 3.0

Example #2 Is HCl a nonpolar covalent or polar covalent bond?

  Step 2: Subtract electronegativities   3.0 – 2.1 = .9

Example #2 Is HCl a nonpolar or polar covalent bond?

  Step 3: check the number line   .9 is between .5 and 1.7

Non-polar covalent

Polar covalent

.5 1.7

Ionic

Example #3 Is NaCl a nonpolar covalent, polar covalent bond, or ionic bond?

  Step 1: Find electronegativity   Na = .9   Cl = 3.0

Example #3 Is NaCl a nonpolar covalent, polar covalent bond, or ionic bond?

  Step 2: Subtract electronegativities   3.0 – .9 = 2.1

Example #3 Is NaCl a nonpolar covalent, polar covalent bond, or ionic bond?

  Step 3: less than .5, between .5 and 1.7, or greater than 1.7?

  2.1 greater than 1.7

Exit Slip 1.  In polar covalent bonds

a.  electrons are equally shared due to similarities in the number of valence electrons

b.  electrons are unequally shared due to differences in electronegativities

c.  electrons are transferred from from one atom to the other

d.  atoms can have more than 8 valence electrons

Exit Slip 2.  Non-polar covalent bonds form when electronegativity

differences a.  are less than .5 b.  more than .5, but less than 1.7 c.  more than 1.7

d.  between .5 and 1.7

Exit Slip 3.  The bond in HI is

a.  non-polar covalent b.  ionic

c.  metallic d.  polar covalent

Exit Slip 4.  Which of the following is a polar covalent bond

a.  H – H b.  H – P

c.  H – Cl d.  H – Na

Exit Slip 5.  Which of the following is a non-polar covalent

compound a.  NaCl b.  Fe3+ c.  CH4

d.  AlCl3

Homework   Finish Lewis symbol and ions worksheet