Mse Glossary

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Amorphous Material

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A material that does not have a long-range order of atoms (e.g., silica glass).

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Anion

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A negatively charged ion produced when an atomic, usually of a nonmetal, accepts one or more electrons.

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Atomic mass

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The mass of the Avagadro number of atoms, g/mol. Normally, this is the average number of protons and neutrons in the atom. Also called the atomic weight.

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Atomic mass unit

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The mass of an atomic expressed as 1/12 the mass of a carbon atom.

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Atomic number

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The number of protons or electrons in an atom.

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Atomic structure

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All atoms and their arrangements that constitute the building blocks of matter.

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Avogadro number

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The number of atoms or molecules in a mol. The avogadro number is 6.02x10^23 per mol.

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Azimuthal quantum number

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A quantum number that designates different energy levels in principal shells.

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Binding energy

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The energy required to separate two atoms from their equilibrium spacing to an infinite distance apart. Alternately, the binding energy is the strength of the bond between two atoms.

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Cation

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A positively charged ion produced when an atomic, usually of a metal, gives up its valence electrons.

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Coefficient of thermal expansion

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The amount by which a material changes its dimensions when the temperature changes. A material with a low coefficient of thermal expansion tends to retain its dimensions when the temperature rises.

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Composition

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The chemical make-up of a material.

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Covalent bond

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The bond formed between two atoms when the atoms share their valence electrons.

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Crystalline materials

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Materials in which atoms are arranged in a periodic fashion exhibiting a long range order.

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Debye interactions

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Van der Waal's forces that occur between two molecules, with only one of them with a permanent dipole moment.

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Directional relationship

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The bonds between atoms in covalently bonded materials from specific angles, depending on the material.

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Ductility

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The ablility of materials to be stretched or bent without breaking.

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Electronegativity

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The relative tendency of an atom to accept an electron and become an anion. Strongly electronegative atoms readily accept electrons.

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Electropositive

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An elemental tendancy for atoms to donate electrons, thus being highly reactive.

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Glass temperature

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A temperature above which many polymers an inorganic glasses no longer behave as brittle materials. They gain a considerable amount of ductility above the glass temperature.

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Hydrogen bond

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A keesom interaction (A type of van der Waals bond) between molecules in which a hydrogen atom is involved.

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Interatomic spacing

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The equilibrium spacing between the centers of two atoms. In the solid elements, the interatomic spacing equals the apparent diameter of the atom.

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Intermetallic compound

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A compound such as Al_3 V formed by two or more metallic atoms; bonding is typically a combination of metallic and ionic bonds.

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Ionic bond

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The bond formed between two different atom species when one atom.