notes 5-3 covalent bonds + - + -. covalent bond a force that bonds two atoms together by a sharing...
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Notes 5-3 Covalent Bonds
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COVALENT BOND• A force that bonds two atoms together by a sharing of
electrons• Each pair of shared electrons creates a bond• Usually occurs between atoms of non-metals
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Example – Water (H2O)
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OH H
How Covalent Bonds Form
How Covalent Bonds Form
The oxygen atom in water and the nitrogen atom in ammonia each have eight valence electrons as a result of forming covalent bonds with hydrogen atoms.
How Covalent Bonds Form
• Double and triple bonds can form when atoms share more than one pair of electrons.
Types of Covalent Bonds
• Different covalent bond types share a different number of electrons
Single Bonds Share 2 Electrons
Double Bonds Share 4
Electrons
Triple Bonds Share 6
Electrons
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Water (H2O) Carbon Dioxide (CO2) Nitrogen (N2)
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Unequal Sharing (Polar Covalent Bond)
Why do you think the two Hydrogen atoms shareequally, but the Hydrogen and fluorine do not?
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Bonded hydrogen atoms showing equal sharing of
electrons
Hydrogen and fluorine bond with
an unequal sharing of electrons
• The unequal sharing of electrons between two atoms that gives rise to negative and positive regions of electric charge
• Results from an atom’s electronegativity – the ability to attract electrons to itself
ElectronCloud
Unequal Sharing of Electrons• Fluorine forms a nonpolar bond with another fluorine
atom. In hydrogen fluoride, fluorine attracts electrons more strongly than hydrogen does, so the bond formed is polar.
Unequal Sharing of Electrons• A carbon dioxide molecule is a nonpolar molecule
because of its straight-line shape. In contrast, a water molecule is a polar molecule because of its bent shape.
Results of BondingMolecule
A neutral group of two or more non-metal atoms held together by covalent bonds
Type:
Diatomic - molecules consisting of two atoms of the same element bonded together
Examples:H2, F2, O2, N2
Compound A pure substance
composed of two or more different elements (atoms) that are chemically combined
Examples:CO, NO2, NaCl
Molecule, Compound, or Both?
H2
Hydrogen
NO2
Nitrogen Dioxide
Cl2
Chlorine
O2
Oxygen
NO
Nitric Oxide
CO2
Carbon Dioxide
N2
Nitrogen
H2O
Water
CH4
Methane
Review Guide
• Pg 130, problems 2a,b,c
• Pg 137, problems 1a, 2a,b,c
• Pg 145, problem 2a
• Pg 163, problems 2a,b,c
• Pg 165-166, problems 1-3, 5-7, 10, 12, 13, 17, 18, 20
• Pg 182, problems 1a,b, 2a,c
• Pg 189, problems 1a,b, 2b,c
• Pg 197, problems 1b,c
• Pg 205-206, problems 1-4, 6, 8, 9, 11, 13, 14, 21-25