Liquids and Solutions and Solids

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Structure and Intermolecular forces

Interactive molecular forces

attractive or repulsive forces between molecules, caused by partial charges. The attractive forces are the ones that work to overcome the randomizing forces of kinetic energy. The structure and type of bonding of a particular substances have quie a bit to do with the types of interaction and the strength of that interaction.

3 types of intermolecular forces

Ion-dipole Intermoelcular Forces

attraction of an ion and one end of a polar molecule (dipole) This type of attraction is especially important in aqueous salt solutions where the ion attracts water molecules and may form a hydrated ion. this is one of the strongest of the intermolecular forces.

Dipole-Dipole Intermoelecular Forces

These forces result from the attraction of the positive end of one dipole to the negative end of another dipole. For example, in gaseous hydrogen chloride, HCl (g) , the hydrogen end has a partial positive charge and the chlorine end has a partial negative charge, due to chlorine's higher electronegativity.

Hydrogen Bond INtermolecular Forces

a special type of dipole-dipole attraction in which a hydrogen atom is polar-covalently bonded to one of the following extremely electronegative elements: N,O, or F. These hydrogen bonds are extremely polar bonds by nature, so there is a greater degree of charge separation whithin the molecule. Therefore, the attraction of the positively charged hydrogen of one molecule and the negatively charged N, O or F of another molecule is extremly strong. These hydrogen bonds are in general, stronger than the typical dipole-dipole interaction

Ion-induced Dipole and Ipole induced Dipole intermolecular Forces

Theses types of attraction occus when the charge on an ion or a dipole distorts the electrons cloud of a nonpolar molecule and induces a temporary dipole in the nonpolar molecule. LIke Ion-dipole intermolecular forces, these also requires two different species. They are fairly week interactions

London (Dispersion) Intermolecular Forces

The intermoelecular attraction occurs in all substances, but is significant only when the other types of intermolecular forces are absent.This is an extremeyly weak interaction, but it is strong enough to allow us to liquefy nonpolar gases such as hydrogen and nitrogen.

3 types of Crystalline Solid States

regular ordering of the particles in a three-dimensional structure called the crystal lattice. IN this crystal lattice there are repeating units called unit cells.

Simple Cubic Unit Cell

particles located at the corner of a simple cube

Body-centered Unit Cell

particles located at the corner of the cube and in the center of the cube

face-centered unit cell

particles at the corners and one in the center of each face of the cube, but not in the center of the cube itself.


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