Glossary of AP Chemistry Atoms

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Quantum Numbers:
n= ?
What does it describe?
n= 1,2,3...
Shells, higher shell number means a greater distance away from nucleus.
Quantum Numbers:
what does it describe?
l = 0,1,2,n-1
Angular momentum quantum number, shape of electron's orbital.
Quantum Numbers:
m(l)= ?
What does it describe?
M(l) = ...-L,-1,0,1,L..
magnetic quantum number, orientation of orbitals in space.
s-> L=0
p-> L=1
d-> L=2
Aufbau Principle
Electrons placed in orbitals, subshells, and shells in order of increasing energy
Pauli Exclusion Principle
Within an atom, no two electrons can have the same set of quantum numbers.
Hund's Rule
Electrons always occupy an empty orbital first...singly, then pair up only if no empty orbitals are avaliable.
Formula: Energy of an Electron
E(n) = (1/n^2)(-2.178x10^(-18)) joules
Electromagnetic radiation
Electrons jump to higher energy levels, when drop, it gives off energy in the form of this radiation.
Formula: Energy and Electromagnetic Radiation
delta E = hf = hc/lambda
planck's constant
6.63x10^(-34) Joule-sec
speed of light
3.00x10^8 m/sec
Dalton's elements
first to say that there are many different kinds of atoms, which combine to form compoundds and same ratio of elements
Dmitri Mendeleev and Lothar Meyer
development of periodic table
Thomson's Experiment
deflection of charges in a cathode ray tube, atoms are composed of positive and negative charges. Plumb pie model.
Milikan's Experiment
oil drops in electric field to calculate charge of an electron
Rutherford's experiment
fired alpha particles at gold foil. Positive chare concentrated in center.
Max Planck
electromagnetic energy is quantized, so energy changes do not occur smoothly but in small specific steps.
Bohr model
electrons orbit at a specific fixed radii, only works for hydrogen
Heisenberg uncertainty principle
impossible to know both the position and momentum of an electron at a particular instant.
An electron orbital is a probability function describing the possibility of an electron at a location.
de Brodlie hypothesis
all matter has wave characteristics.
De Broglie equation
lambda= h / mv
Atomic radius...
decreases across a period
increases down a group
Size of ions...
Cations smaller than atoms
Anions bigger than atoms
Ionization energy
Energy required to remove an electron from an atom
increases across a period
decreases down a group
Electron affinity
measure of the change in energy of an atom when electron is added.
Energy put in when atom becomes less stable...vice versa
how strongly nucleus of an atom attracts electrons of other atoms in a bond
Increases across period
Decreases down a group

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