The stronger the intermolecular forces, the more energy it takes to overcome these interactions and to cause the substance to boil. Therefore, molecules with strong bonds have high boiling points, and molecules with weak bonds have lower boiling points.Continue Reading
The four types of intermolecular forces, listed from strongest to weakest, are ionic, hydrogen bonding, dipole-dipole interactions and Van Der Waals dispersion forces, or London forces.
Ionic forces are interactions between positively and negatively charged atoms or molecules, which attract and bond to each other like magnets. Hydrogen bonding occurs when molecules like oxygen, fluorine and nitrogen, which contain highly electronegative elements, bond to hydrogen. The electronegative atoms pull the hydrogen's electrons toward themselves, creating a partial positive charge on the hydrogen atom and a partial negative charge on the electronegative atom. These partial charges contribute to the strength of intermolecular forces. Dipole-dipole interactions occur when partial charges are created within a molecule that contains electronegative atoms, and the partial charges attract other molecules.
London forces are the weakest intermolecular force. These forces are temporary and occur when electrons are not evenly distributed around the nucleus of the atom. If there are more electrons on one side, a partial charge is created on the atom itself, allowing it to attract other charged atoms or molecules.Learn more about States of Matter
Sodium chloride has a high melting point because of the strong electrostatic attraction between its positive and negative ions; this requires more heat energy to overcome. All ionic compounds have high melting points for this reason.Full Answer >
Intermolecular forces are responsible for the physical properties of a substance, such as its melting or boiling point, viscosity, solubility, surface tension and evaporation. The types of intermolecular forces are ionic, hydrogen bonding, dipole and induced dipole forces. Except ionic force, all other intermolecular forces occur between neutral molecules, which have a slight polarity.Full Answer >
Solids have definite shapes and volumes because their atoms and molecules are held together firmly by the strong inter-molecular forces. At low temperatures, the kinetic energy in the solid is usually not enough to overcome these intermolecular forces, so the solid remains in the same state.Full Answer >
Ideal gases are hypothetical substances studied by scientists and students to simplify intermolecular forces. Ideal gases are point masses that constantly move in a random, straight-line nature. The behavior of ideal gases, meaning the relationship of pressure (P), temperature (T) and volume (V) is summarized as PV=nRT, where "n" is the number of moles of gas. This equation for ideal gases will always equal one.Full Answer >