The electron is found inside a blurry “electron cloud”, also called the “probability region”.

“The more precisely the position of a particle is determined, the less precisely the momentum is known in this instant; and vice versa.”

Describes the region of space where the electron is most likely to be found.

Provides information on the energy of the electron.

Energy is quantized,meaning: can be subdivided into small but measurable increments.

An orbital is not a circular path, rather it is an energy state that can be described by the four quantum numbers.

Principal Quantum Number (n or shell)- the main energy level of an orbital- related to the total energy of the

electron in an atom- represents physically the radial distance

that the probability region extends out from the nucleus

- values: positive integer beginning with 1- 2n2 rule: maximum number of electrons

that can occupy a main energy level

Azimuthal Quantum Number (l)- energy sublevels- defines the shape of the orbital- values: 0 until the integer n-1

lSublev

elOrbital Shape

0 S Spherical1 P Dumbbell-shaped

2 D4 cloverleaf-shaped; 1 dumbbell-shaped w/

ring3 F (too complex to describe)

Magnetic Quantum Number (ml)- describes the orientation of the orbital in space- values: integral value from –l to +l, including 0- formula: 2l + 1 = number of ml values per

sublevel

Sublevel l ml

S 0 0

P 1 -1, 0, 1

D 2-2, -1, 0, 1,

2

Spin Quantum Number (ms)

- represents the electron spin- describes the direction of the spin of

one electron in reaction to the magnetic field generated by another electron nearby.

- values: +½ ( ) – clockwise spin and -½ ( ) – counterclockwise spin

Describes how the electrons are distributed among the orbitals.

Ground state – lowest energy state of the atom;most stable arrangement of the electrons

“The electrons fill the orbitals, one at a time, starting with the lower energy orbital then proceeding to the one

with higher energy.”

n+l rule

- used to identify which orbital has lower energy and is filled up first as electrons are added to the atom.

- the lower the (n+l), the lower the energy

- if (n+l) values are equal, the one with lower n value has the lower energy.

“No two electrons in the same atom can have the same set of four

quantum numbers.”

Consequently, it means: Only two electrons may occupy an orbital, and they must have different spins.

Sublevel# of

orbital

Maximum # of

electrons

S 1 2

P 3 6

D 5 10

F 7 14

“When electrons occupy orbitals of equal energy, they don’t pair up unless all the orbitals have been filled up by a single electron.”

Degenerate orbitals – orbitals or energy levels with the same energy

Paramagnetic Element– has one or more unpaired electrons in its orbital– can be attracted to a magnet

Diamagnetic Element- only paired electrons in its orbitals- slightly repelled by a magnet