What are intermolecular forces? What do intermolecular forces have to do with the states of matter?
I tried googling it, but they gave me really fancy answers and i need something that i will be able to understand
http://en.wikipedia.org/wiki/Intermolecular_force
Based on its molar mass, water should be a gas but because of intermolecular forces water is a liquid at room temperature.
Intermolecular forces are the forces of attraction or repulsion that exist between molecules. These forces play a vital role in determining the physical properties and behavior of substances. To understand intermolecular forces, it's helpful to start with the concept of molecules.
Molecules are made up of two or more atoms bonded together. In a substance, individual molecules interact with each other through intermolecular forces. These forces can be categorized into three main types: London dispersion forces, dipole-dipole interactions, and hydrogen bonding.
1. London dispersion forces: These forces exist between all molecules, regardless of their polarity. They are caused by temporary fluctuations in electron distribution, resulting in temporary partial charges. These temporary partial charges create an attraction between neighboring molecules, holding them together. London dispersion forces are generally the weakest type of intermolecular force.
2. Dipole-dipole interactions: These forces occur between polar molecules. A polar molecule has an uneven distribution of charge, with one end being slightly positive (δ+) and the other end being slightly negative (δ-). This charge imbalance creates a dipole, and the positively charged end of one molecule is attracted to the negatively charged end of another molecule, resulting in dipole-dipole interactions. These forces are stronger than London dispersion forces.
3. Hydrogen bonding: This is a specific type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom such as oxygen, nitrogen, or fluorine. Hydrogen bonding is stronger than regular dipole-dipole interactions. It plays a crucial role in many biological systems and contributes to the unique properties of water.
Now, let's link these intermolecular forces to the different states of matter:
Solid: In a solid state, intermolecular forces are strong enough to hold molecules in a fixed, ordered arrangement. This results in a rigid structure, with minimal molecular movement.
Liquid: In a liquid state, intermolecular forces are weaker than in a solid, allowing the molecules to move more freely. However, they still have enough attraction to stay relatively close to each other. This accounts for the fluidity and the ability of liquids to adopt the shape of their container.
Gas: In a gaseous state, intermolecular forces are very weak compared to the thermal energy or kinetic energy of the molecules. As a result, gas molecules are far apart and move independently at high speeds, filling the entire volume of their container.
Understanding intermolecular forces allows us to explain various properties of substances, such as boiling point, melting point, solubility, and vapor pressure. These forces also affect chemical reactions and play a vital role in determining the phase transitions between different states of matter.