Electromagnetic Radiation
radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum
Blackbody Radiation
the electromagnetic radiation that would be radiated from an ideal black body
Inverse Relation between ? and ?
??=c - where c is the speed of light
c (speed of light)
2.99 E8
Planck's Constant (h)
6.626 E -34
?E =
nh? - Plank dicovered that energy can be gained or lost only by whole number multiples of the quantity h?
Photons
packets of light energy. although light behaves as thought it travels in waves, certain properities of light suggest that it also travels in packets of light energy called photons. these discrete particles of light energy are not tangible entities, but ea
E photon =
h? = hc/?
Photoelectric Effect
the phenomenon in which electrons are emmitted from the surface of a metal when light strikes it.
Threshold Frequency
represents the minimum amount of energy required to remove the electron from the metal's surface
Einstein's Equation
E = mc�
Dual Nature of Light
the statement that light exhibits both wave and particulate properties
de Broglie's Equation
? = h/mv - where v is velocity NOT the frequency
Diffraction
the scattering of light from a regular array of points or lines, producing constructive and destructive interference
Bohr Model
model of the atom in which electrons move rapidly around the nucleus in paths called orbits
Bohr's Equation (Hydrogen atom only)
E = -2.178 E -18 J(Z�/n�) - Z = 1 for Hydrogen (atomic number)
This equation can be used calculate the change in energy when the electron changes orbits
Schrodinger Equation
H? = E? -H represents the mathematical operator
? (wave function)
function of the coordinates x,y, and z of the electron's position in 3d space. .
Orbital
a specific wavefunction for an electron in an atom. The square of this function gives the probability distribution for the electron.
Heisenberg Uncertainty Principle
there is a fundamental limitation to just how precisely we can know both the position and the momentum of the particle at a given time.
Heisenburg Uncertainty Equation
?x � ?p = h/4?
E (for a wave functio) =
n�h�/8mL�
This analysis leads to the a series of slutions to the Schrodinger Equation where each function corresponds to a given energy state.
?(x) (for a particle in a one dimension box) =
?2/L sin (n?/L x)
principal quantum number (n)
First quantum number, designated as the letter "n." It takes on any positive integer value and describes an electron's energy level. An electron with a higher n value is at a higher energy state.
angular momentum number (l)
values range from 0 to n-1 and tells you about the shape of the orbital:
0: s
1: p
2: d
3: f
magnetic quantum number (ml)
ml= -l to l (orientation) orbitals of subshell
ex. at l=2 ml = -2,-1,0,1,2
nodes
areas in an atom of zero probability. the number of nodes increases as n increases
degenerate orbitals
orbitals that have the same value of n and therefore have the same energy
Pauli Exclusion Principle
In a given atom no 2 electrons can have the same set of four quantum numbers (due to the ms spin quantum number)
Ex. If given four specific quantum numbers (n=3, l=1, ml=1, and ms=+1/2) the answer for possible orbitals is 1.
Polyelectronic Atoms
Polyelectronic atoms are atoms that have more than one electron.
Important Note: The Schrodinger Equation only works well for Hyrdogen because it is monoelectronic (one electron). Although the equation aids in the approximation of electron probability, th
Effective Nuclear Charge
Charge experienced by the outermost electrons of an atom: the actual nuclear charge minus the effects of shielding due to inner shell electrons
Zeff = Z(actual) - (effect of electron repulsions)
Aufbau Principle
As protons are added one by one to the nucleus to build up the elements, electrons are similarly added to these atomic orbitals
Hund's Rule
the lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli Principle in a particular set of degenerate orbitals.
(Ex. Orbital Diagram for Carbon)
Valence Electrons
The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds.
Elements in the same group (vertical) on periodic table exhibit the same set of valence electrons.
Exceeptions of Electron Configuration (MEMORIZE)
Cr (Cromium) : [Ar] 4s1 3d5
Cr(Copper) :[Ar] 4s1 3d10
Penetration Effect
the effect whereby a valence electron penetrates the core electron, thus reducing the shielding effect and increasing the effective nuclear energy charge (Zeff)
Ionization Energy
energy required to remove the most loosely held electron (a valence electron)
Ionization Energy increases going across the periodic table and decreases going down.
Exceptions: Oxygen has a lower Ionization Energy than N because of shielding. Oxygen has a
Electron Affinity
The energy change that occurs when an electron is acquired by a neutral atom.
Going across the perodiic table the Electron Affinity values become moe negative.
Going down, the values change very little.
Atomic Radius
one-half the distance between the nuclei of identical atoms that are bonded together
Atomic radius decreases going across the periodic table because of the increasing effective nuclear charge in going from left to right. This means that the valence electr
alkali metals
metallic elements in group 1 of the periodic table which are highly reactive, have a low melting point, good electrical conductivity, and they are soft and shiny when first cut