Chemistry Liquids UHS 2024
PMDC Verified Question 1 of 73
Which type of forces exist between Iodine molecules?
A
Dipole-dipole forces
B
Dipole-induced dipole forces
C
Instantaneous dipole-induced dipole forces
D
Non-polar forces
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Instantaneous dipole-induced dipole forces
Concept:

Intermolecular forces in perfectly non-polar molecules rely solely on the random, temporary movement of electron clouds.

Formula:

Not applicable.

Solution:

  • Iodine (\( \text{I}_2 \)) is a homonuclear diatomic molecule. Because both iodine atoms share the electrons equally, the molecule is perfectly symmetrical and non-polar, possessing a net dipole moment of zero.


  • At any given instant, the large electron cloud can randomly shift to one side, creating a temporary, instantaneous dipole.


  • This temporary dipole distorts the electron cloud of a neighboring \( \text{I}_2 \) molecule, creating an "induced" dipole.


  • The resulting electrostatic attraction is called an Instantaneous dipole-induced dipole force (formally known as London Dispersion Forces).


Why other options are incorrect:

Dipole-dipole forces require permanent polarity, which iodine lacks. Dipole-induced dipole forces require a mixture of polar and non-polar substances.

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