Question

Which are stronger, intermolecular or intramolecular forces for a given molecule? What observation(s) have you made that support this? Explain.

Short answer

In general, intramolecular forces are stronger than intermolecular forces for a given molecule. Observations supporting this include the higher melting and boiling points of ionic compounds compared to covalent compounds and the solubility of ionic compounds in water compared to covalent compounds. These differences in properties can be attributed to the stronger forces within a molecule compared to the weaker forces between molecules.

Step-by-step solution

Introduction to Intermolecular and Intramolecular Forces

Intermolecular forces are the forces that hold molecules together in a substance. These forces include hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Intramolecular forces, on the other hand, are the forces within a molecule that hold the atoms together. These forces include covalent, ionic, and metallic bonds.

Comparison of Intermolecular and Intramolecular Forces

In general, intramolecular forces are stronger than intermolecular forces. This is because the forces that hold atoms together within a molecule, such as covalent and ionic bonds, involve the sharing or transfer of electrons between the atoms. This results in stronger attractive forces between the atoms compared to the weaker forces that exist between separate molecules.

Observation 1: Melting and Boiling Points

One observation that supports the idea that intramolecular forces are stronger than intermolecular forces is the difference in melting and boiling points between ionic and covalent compounds. Ionic compounds, which have strong intramolecular forces, generally have higher melting and boiling points compared to covalent compounds, which are held together by weaker intermolecular forces. This is because the stronger intramolecular forces require more energy to be broken, resulting in higher melting and boiling points.

Observation 2: Solubility in Water

Another observation that supports the idea of stronger intramolecular forces is the solubility of ionic and covalent compounds in water. Ionic compounds, with their strong intramolecular forces, are often soluble in water, as the charged ions can form strong interactions with the polar water molecules, breaking apart the ionic compound. In contrast, covalent compounds with weaker intermolecular forces are often insoluble in water, as their nonpolar nature prevents them from interacting with the polar water molecules.

Conclusion

In summary, intramolecular forces are generally stronger than intermolecular forces for a given molecule. This is supported by observations such as the higher melting and boiling points of ionic compounds compared to covalent compounds and the solubility of ionic compounds in water compared to covalent compounds. These differences in properties can be attributed to the stronger forces within a molecule compared to the weaker forces between molecules.