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A covalent bond occurs when the nuclei of atoms share electrons, resulting in a stable balance of attractive and repulsive electrostatic forces. The potential energy of any system of two atoms capable of forming a covalent bond depends on the distance between the atoms. The more negative the potential energy, the greater the attractive force between the atoms.

Bond energy is the amount of energy released when a bond is formed, which is equivalent to the absolute value of the potential energy of two atoms in a covalent bond. Bonds of higher energies are more stable than bonds of lower energies. Bond length is the average distance between the nuclei of atoms in a covalent bond. Bond order is the number of electron pairs shared between the two atoms. For diatomic molecules, bond energy is equivalent to the dissociation energy, which is the amount of energy required to pull apart the atoms in a diatomic molecule.

Figure 1 shows the potential energy curve for a system of two hydrogen atoms. Table 1 presents bond lengths and energies for covalent bonds of varying orders. Table 2 presents the bond length and dissociation energies for a number of diatomic molecules.

Figure 1


Table 1

bond

bond order

bond length (pm)

bond energy (kJ/mol)

C–C

1

154

347

C=C

2

134

612

C≡C

3

120

837

N–N

1

145

163

N=N

2

123

418

N≡N

3

110

946

C–O

1

143

360

C=O

2

120

736


Table 2

molecule

dissociation energy (kJ/mol)

bond length (pm)

H2

432

74

N2

946

110

O2

495

121

F2

158

142

Cl2

237

199

Sources:
http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html
http://www.wiredchemist.com/ch...

Choose the option that best answers the question.

Based on information in the passage and Figure 1, as the distance between two hydrogen atoms decreases, the attractive force between the atoms:

Title

A covalent bond occurs

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Correct

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