1. Intramolecular Forces: These are the forces that hold atoms together within a molecule. They are much stronger than intermolecular forces.
* Covalent Bonds: The strongest type of intramolecular force. They involve the sharing of electrons between atoms. Examples include the bonds in water (H₂O) and methane (CH₄).
* Ionic Bonds: These involve the electrostatic attraction between oppositely charged ions. They are not typically found within molecules, but rather between molecules in ionic compounds.
* Metallic Bonds: These occur in metals and involve a "sea" of delocalized electrons shared by all the metal atoms.
2. Intermolecular Forces: These are the forces that exist *between* molecules. They are much weaker than intramolecular forces but still play a significant role in determining a substance's physical properties, such as melting point and boiling point.
* Hydrogen Bonding: A strong type of dipole-dipole interaction that occurs when a hydrogen atom is bonded to a highly electronegative atom, such as oxygen or nitrogen. This is crucial for the properties of water.
* Dipole-Dipole Interactions: Occur between polar molecules due to the attraction of oppositely charged ends.
* London Dispersion Forces: These are temporary, weak attractions that occur between all molecules due to instantaneous fluctuations in electron distribution. They are the weakest intermolecular force.
To summarize, the forces that hold a molecule together are called intramolecular forces, mainly covalent bonds. The forces that act between molecules are called intermolecular forces, which are much weaker and include hydrogen bonding, dipole-dipole interactions, and London dispersion forces.
