Transcript Chemical bond - Christopher Dock Mennonite High School

Types of bonds
• Ionic
• Covalent
• metallic
Covalent bonding
• Results from the sharing of electrons pairs
between two atoms.
Covalent bonding
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Electronegativity difference
Bonding ‘story’
Bond length
Bond energy
Octet
Octet exceptions
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H
B
S
Xe
Metallic bonding
• Bonding that results from the attraction
between metal atoms and the surrounding
“sea of electrons”
– Delocalized electrons – electrons that freely
move around; empty orbitals overlap, electrons
very mobile making a “sea” of electrons
Metallic bonds
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Sea of electrons
Metallic properties
Luster
Malleability
Ductility
Heat of vaporization
Lewis structures
• Valence electrons by dots.
• Lone pair – unshared pair
Multiple bonds
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Single bond
Double bond
Triple bond
Strength?
How can you tell if a bond is
ionic or covalent?
• A bond is rarely purely ionic or covalent.
Usually falls somewhere between the two
extremes.
• Diatomic – covalent
electronegativity
• Measure of an atom’s ability to attract
electrons.
• The degree to which bond is ionic or
covalent depends on the difference in
electronegativities.
How to do
• Look up the electronegativities of the atoms
involved on a chart.
• Subtract the two numbers
• Find where they fall on the ionic- covalent
scale.
Polar
• Polar – an unequal sharing of electrons that
lends a molecule to be partially negative at
one end and partially positive at another.
Water is an example.
Reading the chart
• Values above 1.7 are ionic, the closer you
are to 3.3 the more ionic.
• Values under 1.7 are covalent.
– Values under 0.3 are nonpolar -covalent
– Values between 1.7 and .3 are polar -covalent