Electronic Structure of Atoms

Heisenberg Uncertainty Principle
A principle that states we can never know both the position and velocity of an electron beyond a certain level of precision.
Shows the probability of finding an electron within a given volume of space around the nucleus. The number in a shell is equal to the shell number squared.
A grouping of orbitals based on their principle quantum number (n).
A grouping of orbitals based on their the angular momentum quantum number (l). Referred to by letter rather than number (s, p, d, f, g). The number of these is equal to the shell number.
Pauli Exclusion Principle
A maximum of two electrons can occupy a single orbital and they must have opposite spins.
Aufbau Principle
Fill lower energy orbitals with electrons before filling higher energy orbitals.
Hund’s Rule
If two or more orbitals with the same energy are available, half fill each orbital with 1 electron before filling any one orbital. The electrons in half-filled orbitals should have the same spin direction (parallel spins).
Orbitals that have the same energy level.
Ground-state Electron Configuration
The lowest energy configuration of electrons in orbitals.
s-block elements
Elements in groups 1A and 2A that have electron configurations where the s orbital is the last orbital filled.
p-block elements
The elements in groups 3A through 8A who have an electron configuration where the p orbital is the last orbital filled.
d-block elements
The transition metal elements that have electron configurations where the d orbital is the last orbital filled.
f-block elements
The inner-transition metal elements which have electron configurations where the f orbital is the last orbital filled.
Atomic Radii
The radius of an atom. Decreases from left to right across a period on the periodic table. Increases from top to bottom down a group on the periodic table. Depends on the effective nuclear charge.
Effective Nuclear Charge
The net nuclear charge actually felt by an electron (Zeff)
principle quantum number


gives the electron shell and the relative energy of electrons; higher values of n represent larger orbitals with electrons at higher energy levels

angular momentum quantum number



can have integer values of 0 to n-1


defines the shape of an orbital (0, s; 1, p; 2, d; 3, f)

magnetic quantum number


can have integer values from –1 to +l, including 0

give the spatial orientation of the orbital and indicates the number of an orbital shape per electron shell

spin magnetic quantum number


has possible values of +1/2 and -1/2


indicates the magnetic spin of an electron in a specific orbital




the distance between two adjacent peaks in a wave




the number of complete wavelengths that pass a given point each second



speed of light



3.00 x 108 m/s


unit of distance


1 x 109 nm = 1 m

Plank’s constant



6.626 x 10-34

Equation relating frequency and wavelength
c = ??
Equation relating energy of a photon and frequency
E = h?
Energy of a photon



measured in J

Equation relating energy of a photon to wavelength
E = (hc)/?

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