Bonding Intro 2016.notebook
March 18, 2016
Unit 9: Chemical Bonding
Textbook Chapter 12
Review Book Chapter 6
What is a chemical bond?
A chemical bond is a sharing or transfer of valence electrons from one atom to another
Aim: Why do atoms bond? What kinds of bonds can they form?
Dec 1­4:53 PM
Dec 1­4:59 PM
Why do elements bond?
Atoms bond to become more stable.
Two ways that bonding results in a more stable atom:
• Form a stable electron configuration (stable octet)
• Forming a bond releases energy
­Lower energy results in a more stable substance.
Dec 1­5:12 PM
In the main types of chemical bonds electrons are either transferred, shared or mobile.
Electronegativity is the property that determines the type of bond an atom will form with different types of elements.
Large electronegativity difference: electrons are transferred.
No electronegativity difference: electrons are shared equally.
Small electronegativity difference: electrons are shared unequally.
Dec 1­5:01 PM
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Bonding Intro 2016.notebook
March 18, 2016
IONIC BONDS
METALLIC BONDS
An ionic bond is formed when electrons are transferred from the metal to the nonmetal to give each atom a stable octet.
• A metallic bond forms between atoms of the SAME metal ONLY
• There is an attraction between the valence electrons and all of the metal cations which causes the e­ to be mobile.
• A metallic bond contains a “sea of mobile electrons”
• The bond is an attraction between the oppositely charged IONS
• Ionic compounds are called “Salts”
• Ionic bonds have an E.N. difference of 1.7 or greater.
• Ionic bonding also occurs in compounds that contain a polyatomic ion Dec 1­5:12 PM
Dec 1­5:12 PM
COVALENT BONDS
A covalent bond is formed when two nonmetal atoms share a pair of electrons in order to achieve a stable octet
Types of Covalent Bonds
H
Cl
H
NONPOLAR COVALENT
BOND
Dec 1­5:41 PM
H
POLAR COVALENT
BOND
Nonpolar covalent bonds occur between two identical nonmetal atoms.
Polar covalent bonds occur between two different nonmetal atoms.
Equal sharing of electrons
Unequal sharing of electrons
EN difference between atoms = 0
EN difference range of 0 ­1.7
Dec 1­5:30 PM
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Bonding Intro 2016.notebook
March 18, 2016
Covalent Bonds
How many electrons are shared in each of these bonds?
SINGLE BOND
DOUBLE BOND TRIPLE BOND
Dec 1­5:43 PM
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