Name: ____________________________________________________
Electron Configurations and Orbital Diagrams Review:
There are two ways to organize the information from electrons:
Orbital Diagrams
and
Electron Configurations
1s2 2s2 2p2
The big number =___________________
Each arrow represents an electron.
Each line represents an __________, the
sublevel and energy level are written below
The spaces separate sublevels
*notice that there are 3 lines for p since p
has 3 different ___________
Letter = ______________
Exponent = # of _____________ in that
sublevel
This method does not give as much
information as orbital diagrams.
Here are some rules for writing orbital
diagrams and electron configurations:
Aufbau Principle: An electron occupies
the lowest energy orbital that can
receive it
Each arrow represents an electron.
The big number = energy level
Each line represents an orbital, the sublevel
and energy level are written below
Low Energy
The spaces separate sublevels
Letter = sublevel
Exponent = # of electrons in that sublevel
High Energy
*notice that there are 3 lines for p since p has 3
1s2 2s2 2p6 3s2 3p6different
4s2 3d10
4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10
orbitals
Pauli Exclusion Principle:
This method does not give as much
information s orbital diagrams.
No two electrons in the same atom can have the same set of four quantum numbers
Hund’s Rule
1. Orbitals of the same energy are occupied by on electron before any orbital is occupied by a second electron
2. All electrons in singly occupied orbitals must have the same spin.
Identify the problem with each orbital diagram below:
a.
b.
c.
Orbital Diagrams
1.
2.
3.
4.
Determine the number of electrons from the atomic number on the periodic table
Determine the highest energy level
Draw lines for each of the orbitals available to each energy level
Fill in electrons using up and down arrows according to Aufbau, Hund, and Pauli principles
Write the Orbital Diagrams for:
Lithium
Fluorine
Electron Configurations
1.
2.
3.
4.
5.
Determine the number of electrons using the atomic number from the periodic table
Write the energy level number
Write the orbital number
Write the number of electrons in that orbital as a superscript
Repeat until all electrons have been used
Write the Electron Configuration for:
Calcium
Phosphorus
Noble Gas Configurations: These are a shorter version of electron configurations
1. Identify the noble gas that comes BEFORE the element you are writing the electron configuration for – EVEN IF
IT IS FARTHER AWAY.
2. Put the noble gas in square brackets
3. Write the rest of the electron configuration
Ne:
1s2 2s2 2p6
Na:
1s2 2s2 2p6 3s1
Notice the similarity of Na and Ne?
Abbreviate Na's electron configuration : [Ne] 3s1
Electron Configurations for Ions: Follow the same procedures as previous examples:
Na+ has 10 electrons instead of 11
Write the electron configuration so that
exponents add up to 10
Na:
Na+:
O2- has 8 electrons instead of 6
O:
1s2 2s2 2p6 3s1
1s2 2s2 2p4
O2-: 1s2 2s2 2p6
1s2 2s2 2p6
Notice that the electron configuration for the sodium ion is now the same as Neons. Remember, elements
react to become stable, like their nearest noble gas. In Na's case, it's neon.
Ca+2
F-1
There are 4 kinds of sublevels: s, p, d, f
Here's what they look like:
s orbitals are just spheres:
p orbitals have two lobes and there are 3 different p
orbitals (one for each axis: px, py, pz)
d orbitals are more complicated, one of them is just
odd. 5 different d orbitals:
f orbitals are a lot more complicated. There are seven
of them.
Periodic Trends
This is a map!
If I say tell me the element that
ends with 5p2 you would
Patterns on the periodic table:
o s orbitals can hold __________________, all elements in the ____________________ on the PT have
electron configurations than end with s1 (group 1) or s2 (group 2)
o The p sublevel can hold _____________________ and there are ________________ that correspond to
ending electron configs of p1, p2, p3 and so on.
o The d sublevel can hold ____________________________ and there are __________________ that
correspond to ending electron configurations of d1, d2, d3 and so on.
o The f sublevel can hold __________________ and there are __________________ that correspond to
ending electron configurations of f1, f2, f3 and so on.
o The energy level is the same as the row/period number
o except for d electrons which are one less than the row number
o except for f electrons, but this is easy to remember because the first time f electrons show up is in
the fourth energy level, so the first row of the f section is 4f and the second row is 5f
o Notice that each of the sections generally corresponds to elements that have similar properties
o
S BLOCK: Alkali metals and alkaline earth: react strongly with water, are metallic and form only one type of
ion
o P BLOCK: Mostly the non-metals (it also includes some metals)
o D BLOCK: Transition metals: metallic, have multiple oxidation states, often form colored compounds.
o F BLOCK: Many are radioactive/unstable
Periodic Trends:


Shielding: As you go down the periodic table, the number of shells increases which results in greater
electron-electron repulsion.
o The more shells there are, the further from the nucleus the valence electrons are.
o Therefore, more shielding means the electrons are ______________ attracted to the nucleus of
the atom.
Atomic Radius is defined as half the distance between adjacent nuclei of the same element.
o As you move DOWN a group an entire energy level is added with each new row, therefore the
atomic radius ___________________.
o As you move LEFT-TO-RIGHT across a period, a proton is added, so the nucleus more strongly
attracts the electrons of an atom, and atomic radius ___________________________.

Isoelectronic Ions: Ions of different elements that contain the same number of electrons.

Ionization energy is defined as the energy required to _______________ the first electron from an atom.
o As you move down a group atomic size increases, allowing electrons to be further from the
nucleus, therefore the ionization energy ______________________.
o As you move left-to-right across a period, the nuclear charge increases, making it harder to remove
an electron, thus the ionization energy ______________________.

Electronegativity is defined as the relative ability of an atom to attract electrons in a
____________________________________.
o As you move down a group atomic size increases, causing available electrons to be further from the
nucleus, therefore the electronegativity ______________________.
o As you move left-to-right across a period, the nuclear charge increases, making it easier to gain an
electron, thus the electronegativity _________________________.
o Noble Gasses have a very ______ electronegativity.
Quantum Numbers: Four quantum numbers: n, l, ml, ms




The quantum mechanical model uses three quantum numbers, n, l and ml to describe an orbital in
an atom. A fourth quantum number, ms, describes an individual electron in an orbital.
n = energy level
o This describes the energy level and can be described as an integer from 1-7. The larger the
number, the larger the orbital. As the numbers increase, the electron will have greater
energy and will be less tightly bound by the nucleus.
l = angular momentum (orbital shape: s, p, d, f)
o This describes the shape of the orbital level and can be described as an integer from 0 to n1.
o 0 is used to describe s orbitals; 1 is used to describe p orbitals.
o 2 is used to describe d orbitals; 3 is used to describe f orbitals.
ml= Magnetic (axis: x, y, z)
o This describes the orientation of the orbital in space and can be described as an integer
from -l to l
o s sublevels have one orbital, therefore possible values of ml include 0 only.
o p sublevels have three orbitals, therefore possible values of ml include -1, 0, 1.
o d sublevels have five orbitals, therefore possible values of ml include -2, -1, 0, 1, 2.
o What about f?

ms= spin (up or down arrow)
o This describes the spin of the electron in the orbital.
o The possible values for ms are +½ and ½.
o The positive spin reflects the first electron in a specific orbital and negative spin reflects the
second electron in an orbital.



Determine the energy level of the electron
Assign 1 for energy level 1, 2 for level 2, etc.
Determine the orbital
Orbital
Angular Momentum
Quantum Number
s
p
d
f
Determine the axis (degenerate orbital) that the electron is on
Orbital
Magnetic Quantum Number
s
0
p
-1
0
+1
d
-2
-1
0
+1
+2


Determine the
spin

Up = + ½

Down = - ½

Examples:
o Give the four quantum numbers for the 8th electron in Argon:
o What is the maximum number of electrons that can have the following quantum numbers:
n = 2 and ms = -½
o Which of the following quantum numbers would NOT be allowed in an atom
n = 2, l = 2 and ml = -1
n = 4, l = 2 and ml = -1
n = 3, l = 1 and ml = 0
n = 5, l = 0 and ml = 1
Review Questions:
1. With n representing the outermost energy level, the electron configuration for elements present in
group 14 is
a. ns2np1
b. ns2np4
c. ns2np2
d. ns2np3
2. Which of the following describes what takes place when iron (Fe0) is oxidized to Fe+2 ions ?
a. a gain of two protons
b. a loss of two electrons
c. a gain of two electrons
d. a loss of two protons
4. Which of these trends describes a tendency for atomic radii as displayed on the periodic chart ?
a. Atomic radii increase left to right across a period
b. Atomic radii decrease left to right across a period
c. Atomic radii decrease top to bottom down a group
d. Atomic radii increase, then decrease from top to bottom down a group
5. Which grouping identifies chemical properties?
a. Malleability, ductility, conductivity
b. Luster, hardness, texture
c. Combustibility, flammability, reactivity
d. Density, melting point, boiling point
6. The elements that are characterized by having only five electrons in the p sublevel belong to which
family of elements?
a. transition
b. Halogens
c. Noble gas
d. Alkali
Exit Ticket: You must answer all questions and fill out all information to receive the bonus points.
5/2/13 Review Session: Orbital Diagrams and Electron Configurations:
Name: ______________________________________________ Teacher:_____________________ Block:________
1. Write one question that you have regarding the material covered today.
2. Write an electron configuration for phosphorus:
3. Circle the larger element below
a. Mg or Cl
b. N or Sb
c. O-2 or Mg+2
4. Circle the most electronegative element for each question below
a. Na or S
b. Br or F
c. Ar or Si