Mole Fraction: Concentration of a substance in a mixture measured as moles of the substance per mole of mixture. For example, the mole fraction of oxygen in air is about 0.21, which means that 1 mol of air contains about 0.21 mol O2.

 

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Mole Fraction: Concentration of a substance in a mixture measured as moles of the substance per mole of mixture. For example, the mole fraction of oxygen in air is about 0.21, which means that 1 mol of air . . . View Full Definition

Moleskin: Soft material that reduces friction and protects skin.

Nonpolar Molecule: A molecule in which the center of positive charge and the center of negative charge coincide. Examples are ccl4 and CO2; counterexamples are chcl3 and H2O.

Polar Molecule: An asymmetric molecule containing polar bonds. H2O, NH3, and hcl are examples of polar molecules. Non-examples are CO2, ccl4, and bcl3 which contain polar bonds but are nonpolar because they . . . View Full Definition

Molecules: Units of two or more atoms held together by chemical bonds. The combination of atoms by chemical bonds with the component atoms in definite porportions, such as water (two H to one O).

Molecule: The smallest particle of an element or compound that retains the chemical properties of the element or compound. A molecule is a collection of chemically bound atoms with characteristic comp . . . View Full Definition

Molecular Model: A representation of a molecule. The model can be purely computational or it can be an actual physical object. Stick models show bonds, ball-and-stick models show bonds and atoms, and spacefi . . . View Full Definition

Molecular Orbital: A wavefunction that describes the behavior of an electron in a molecule. Molecular orbitals are usually spread across many atoms in the molecule, and they are often described as a combinatio . . . View Full Definition

Molecular Sieve: A material that contains many small cavities interconnected with pores of precisely uniform size. Zeolites are an example. Molecular sieves adsorb molecules that are small enough to pass thr . . . View Full Definition

Molecular Weight: The average mass of a molecule, calculated by summing the atomic weights of atoms in the molecular formula. Note that the words mass and weight are often used interchangeably in chemistry.