Electronic Structure of Atoms

electronic structure
the arrangement of electrons in an atom or molecule
electromagnetic radiation
a form of energy that has awave characteristics and that propagates through a vacuum at the characteristic speed of 3.00*10^8 m/s
wavelength
the distance between identical points on successive waves
frequency
the number of times per second that one complete wavelength passes a given point
quatum
the smallest increment of radiant energy that may be absorbed or emitted the magnitude of radiant energy is hv
Planck’s constant
the constant that relates the energy and frequency of a photon E = hv; equals 6.626*10^-34 J-s
photoelectric effect
the emissions of electrons from a metal surface induced by light
spectrum
the distribution among various wavelengths of the radiant energy emitted or absorbed by an object
continuous spectrum
a spectrum that contains radiation distributed over all wavelengths
line spectrum
a spectrum that contains radiation at only certain specific wavelengths
ground state
the lowest energy, or most stable, state
excited states
a higher energy state than the ground state
matter waves
the term used to describe the wave characteristics of a moving particle
momentum
the product of the mass and velocity of an object
uncertainty principle
a principle stating there is an inherent uncertainty in the precision with which we can simultaneously specify the position and momentum of a particle this uncertainty is significant only for particles of extremely small mass, such as electrons
wave functions
a mathematical description of an allowed energy state (an orbital)
probability density
a value the represents the probability that an electron will be found at a given point in space
electron density
the probability of finding tan electron at any particular point in an atom; this probability is equal to the square of the wave function
orbitals
an allowed energy state of an electron in the quantum mechanical model of the atom; the term orbital is also used to describe the spatial distribution of the electron; an orbital is defind the the values of three quantum numbers: n, l, and ml
electron shell
a collection of orbitals that have the same value of n
subshell
one or more orbitals with the same set of quantum numbers n and l
radial probability function
the probability that the electron will be found at a certain distance from the nucleus
nodes
points in an atom at which the electron density is zero; for example the node in a 2s orbital is spherical surface
degenerate
a situation in which two or more orbitals have the same energy
electron spin
a property of the electron that makes it behave as though it were a tiny magnet; the electron behaves as if it were spinning on its axis; electron spin is quantized
spin magnetic quantum number
a quantum number associated with the electron spin
Pauli exclusion principle
a rule stating that no two electrons in an atom may have the same four quantum numbers; as a reflection of this principle, there can be no more than two electrons in any one atomic orbital
electron configuration
the arrangement of electrons in the orbitals of an atom or molecule
Hund’s rule
a rule stating that electrons occupy degenerate orbitals in such a way as to maximize the number of electrons with the same spin; in other words, each orbital has one electron placed in it before pairing of electrons in orbitals occurs
valence electrons
the outermost electrons of an atom; those that occupy orbitals not occupied in the nearest noble-gas element of lower atomic number; the valence electrons are the ones the atom uses in bonding
core electrons
the electrons that are not in the outermost shell of an atom
representative elements
an element from within the s and p blocks of the periodic table
main-group elements
elements in the s and p blocks of the periodic table
transition elements
elements in which the d orbitals are partially occupied
lanthanide (rare earth) elements
element in which the 4f subshell is only partially occupied
actinide elements
element in which the 5f orbitals are only partially occupied
f-block metals
lanthanide and actinide elements in which the 4f and 5f orbitals are partially occupied