Notes 5-3 Covalent Bonds

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

Cl2Chlorine

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