| A | B |
|---|
| Model | A simplified approximation of reality. |
| Solid | A state having a definite shape and volume at constant T. |
| Liquid | A state having a variable shape and constant volume at constant T |
| Gas | A state having a definite shape and volume at constant T. |
| Evaporation | The conversion of a liquid to a gas at T below its boiling point. |
| Vaporization | The conversion of a liquid to a gas at its boiling point |
| Element | A pure substance that cannot be chemically converted into simpler substances. |
| Group | All the elements in a given column of the Periodic Table (also called a Family). |
| Metals | Elements with metallic luster that conduct heat/electricity well, are malleable. |
| Malleable | Able to be shaped by hammer blows. |
| Nonmetals | Solid, liquid or gaseous elements lacking metallic luster, are non-conductors of heat/electrocity, brittle solids. |
| Metalloids | Elements that have some, but not all characteristics of metals; also called semimetals. |
| Representative elements | Elements in groups 1, 2, and 13 - 18 ("A" group); also called "main-group". |
| Transition metals | Elements in groups 3 through 12 ("B" group) |
| Inner transition elements | The 28 elements in the rows pictured outside the main periodic table. |
| Periods | Horizontal rows on the periodic table. |
| Atom | The smallest unit of an element that maintains the chemical characteristics of that element. |
| amu | Atomic mass unit equal to 12th of the mass of a Carbon-12 atom. |
| Proton | A positively charged particle found in the nucleus of an atom, mass = 1amu |
| Electron | A negatively charged particle found in the electron cloud of an atom, mass = 1/1860 amu. |
| Neutron | An uncharged particle fount in the nucleus of an atom, mass = 1 amu. |
| Nucleus | An extremely small, positively charged central core of an atom; volume is 1/10,000 of the atom. |
| Ion | Any positively or negatively charged particle. |
| Cation | A positive ion formed by the loss of electrons by an atom. |
| Anion | A negative ion formed by the gain of an electron by an atom |
| Isotope | Atoms of the same element which differ in their number of neutrons. |
| Atomic number | The number of protons in an atom's nucleus. Determines the atom's identity. |
| Mass number | The sum of the number of protons and neutrons in an atom's nucleus. |
| Covalent bond | A link holding two atoms together; results from two atoms sharing a pair of electrons |
| Molecule | An uncharged collection of atoms held together by covalent bonds. |
| Diatomic | A molecule composed of a pair of atoms; e.g. H2, N2, O2, F2, Cl2, Br2 and I2. |
