Answer to Question #101934 in General Chemistry for jude

Question

5. a) Explain the difference between intermolecular forces and intramolecular forces.
b) Explain the terms ‘polar covalent bond’ and ‘dipole’.
c) Describe and explain, using appropriate examples, how the following intermolecular forces arise:
i) Instantaneous dipole – induced dipole (London forces)
ii) Permanent dipole – permanent dipole
iii) Hydrogen bonds

Answer 1

When the bond is in one molecule of a compound then it is intramolecular.

When the bond is in between the 2 or more molecules of a compound then it is intermolecular. Intramolecular bond is stronger since distance is low.

Electrons in covalent compounds are rarely exactly equally "shared" by all the atoms. Rather the electrons have a greater relative attraction for more electro negative atoms compared to less electro negative.

This is the reason why dipole is created in the molecule.

London Forces are the weakest of the intermolecular forces and exist between all types of molecules, whether ionic or covalent—polar or nonpolar. The more electrons a molecule has, the stronger the London dispersion forces are.

Dipole-dipole interactions: These forces occur when the partially positively charged part of a molecule interacts with the partially negatively charged part of the neighboring molecule. The prerequisite for this type of attraction to exist is partially charged ions—for example, the case of polar covalent bonds such as hydrogen chloride, H, C, l, end text. Dipole-dipole interactions are the strongest intermolecular force of attraction.

Hydrogen bonding: This is a special kind of dipole-dipole interaction that occurs specifically between a hydrogen atom bonded to either an oxygen, nitrogen, or fluorine atom. The partially positive end of hydrogen is attracted to the partially negative end of the oxygen, nitrogen, or fluorine of another molecule. Hydrogen bonding is a relatively strong force of attraction between molecules, and considerable energy is required to break hydrogen bonds. This explains the exceptionally high boiling points and melting points of compounds like water, \text{H}_{2}\text{O}H

2

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Ostart text, H, end , start subscript, 2, end subscript, start text, O, end text, and hydrogen fluoride, HFstart text, H, F, end