| A | B |
|---|
| Alpha Particle | A Helium ion with 2+ charge; 2 protons and 2 neutrons |
| angstrom (A) | 10^-10 meter |
| atomic radius | the radius of an atom |
| atomic number | the number of protons- defines the identity of an element |
| atomic orbital | the region or volume in space in which the probability of finding electrons is the highest |
| aufbau principle | describes the order in which electrons fill orbitals in atoms |
| degenerate | of the same energy |
| d Orbitals | beginning in the third energy level, a set of five degenerate orbitals per energy level |
| effective nuclear charge (Zeff) | the nuclear charge experienced by the outermost electrons of an atom; the actual nuclear charge minus the effects of shielding due to inner shell electrond |
| electron affinity | the amount of energy absorbed in the process in which an electron is added to a neutral gaseous atom to form a gaseous ion with a 1- charge; has a negative value if energy is released |
| electron configuration | specific distribution of electrons in the atomic orbitals of atoms or ions |
| electronegativity | a measure of the relative tendency of an atom to attract electrons to itself when chemically combined with another atom |
| excited state | any other state other than the ground state of an atom or molecule |
| f orbitals | beginning in the fourth energy level, a set of seven degenerate orbitals per energy level |
| ground state | the lowest energy state or most stable state of an atom, molecule, or ion |
| group | a vertical column in the periodic table |
| heisenberg uncertainty principle | it is impossible to determine accurately both the momentum and position of an electron simultaneously |
| hund's rule | all orbitals of a given sublevel must be occupied by single electrons before pairing begins |
| inner transition elements | elements 58 through 71 and 90 through 103 |
| ionic radius | the radius of an ion |
| ionization energy | the minimum amount of energy required to remove the most loosely held electron of an isolated gaseous atom or ion |
| isoelectronic | having the same electron configurations |
| magnetic quantum number | quantum mechanical solution to a wave equation that designates the particular orbital within a given set (s,p,d,f) in which an electron resides |
| nanometer (nm) | 10^-9 meter |
| noble gases | rare/inert gases |
| nuclide symbol | the symbol for an atom in which E is the number for an element, Z is the atomic number, and A is its mass number |
| Pauli Exclusion Principle | no two electrons in the same atom may have identical sets of four quantum numbers |
| period | a horizontal row in the periodic table |
| periodicity | regular periodic variations of properties of elements with atomic number |
| p orbitals | beginning with the second energy level, a set of three mutually perpendicular, equal-arm, dumbbel-shaped atomic orbitals per energy level |
| principal quantum number (n) | the quantum mechanical solution to a wave equation that designates the major energy level, or shell, in which an electron resides |
| quantum mechanics | a mathematical method of treating particles on the basis of quantum theory, which assumes that energy (of small packets) is not infinitely divisible |
| quantum numbers | numbers that describes the energies of electrons in atoms; derived from quantum mechanical treatment |
| s orbital | a spherically symmetrical atomic orbital; one per energy level |
| spin quantum number | the quantum mechanical solution to a wave equation that indicates the relative spins of electrons |
| subsidiary quantum number (l) | the quantum mechanical solution to a wave equation that designates the sublevel, or set of orbitals (s,p,d,f,) within a given major energy level in which an electron resides |
| paramagnetism | a type of induced magnetism, associated with unpaired electrons, that causes a substance to be attracted into the inducing magnetic field |
| diamagnetism | a type of magnetism, associated with paired electrons, that causes a substance to be repelled from the inducing magnetic field |
