Transcript Electron Configurations

-the arrangement of electrons in an atom
-a distinct configuration for each element
-assume the arrangement with the lowest possible energies
(ground-state electron configuration)
1. Aufbau Principle
2. Pauli Exclusion Principle
3. Hund’s Rule
-shows the order in which
electrons occupy orbitals
-states: an electron occupies
the lowest-energy orbital that
can receive it
Ex: lowest energy orbital is ls;
the H electron occupies this
orbital
-beginning with the 3rd main
energy level, the energies of
the sublevels begin to overlap
-reflects the importance of the
spin quantum number
-states: no two electrons in the
same atom can have the same set
of four quantum numbers
1s orbital
-orbitals of equal energy are each occupied by one electron
before any orbital is occupied by a second electron, and all
electrons in singly occupied orbitals must have the same spin
Ex: p sublevel being filled
1. ____ ____ ____
2. ____ ____ ____
3. ____ ____ ____
4. ____ ____ ____
It is unpaired electrons that
cause an element to be
magnetic. Paramagnetism
means weakly attracted
due to unpaired electrons.
There are three methods, or notations, used to indicate
electron configurations. They are:
Orbital Notation
Electron-Configuration Notation
Noble-Gas Notation
-unoccupied level is ____ with orbital name underneath
- ____ = orbital with 1 electron
- ____ = orbital with 2 electrons, paired with opposite spins
Ex: H ____
1s
He ____
1s
B ____ ____ ____ ____ ____
1s 2s 2px 2py 2pz
-eliminates the lines and
arrows of orbital notation
-add superscript to
sublevel designation
Ex: H 1s
1
He 1s
2
B 1s 2s 2p
2
2
1
Electrons fill the areas which require the least amount of
energy, and it takes less energy to fill the 4s than it does to
fill the 3d. So, as soon as the 3p is filled the very next
thing to begin to fill is the 4s, then the 3d fills and then the
4p. The orbits themselves are not overlapping – there is
some overlapping of the energy of each of the orbits. To
help us tell what will fill next, we will learn to use the
Periodic Table.
-”s” and “p” electrons: main
energy level # same as the -”d” electrons: main energy level
period #
# ONE LESS than the period #
-”f” electrons: main energy level #
TWO LESS than the period #
-highest occupied level: the e- containing main energy level
with the highest principal quantum number
-inner shell electrons: electrons that are not in the highest
occupied energy level
-octet: “s” and “p” sublevels of highest energy level filled
with 8 electrons
Noble Gases – the Group 18 elements
(He, Ne, Ar, Kr, Xe, Rn)
Noble Gas Configuration: an outer main energy
level fully occupied, in most cases, by 8 e-use noble gas’s symbol in brackets to
denote that much of the econfiguration, then add the remaining
e- configuration
Ex: Na = [Ne]3s1
1s 2s 3s 4s 5s 6s 7s
2p 3p 4p 5p 6p 7p
Set up the s sublevels,
then the p, d, and f.
Follow the arrows in
filling each successive
orbital.
3d 4d 5d 6d 7d
4f 5f 6f 7f
5g 6g 7g