Notes 5-3 Covalent Bonds + - + -. COVALENT BOND A force that bonds two atoms together by a sharing of electrons Each pair of shared electrons creates.

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