AP Chemistry
Unit 3 - Elements
Lesson 10 – Electron
Configurations
Book Section: 6.4-6.9
Electron Configurations


This shows the
distribution of all
electrons in an atom.
Each component
consists of

A number denoting the
energy level;
Electron Configurations


This shows the
distribution of all
electrons in an atom.
Each component
consists of


A number denoting the
energy level,
A letter denoting the
type of orbital,
Electron Configurations


This shows the
distribution of all
electrons in an atom.
Each component
consists of



A number denoting the
energy level,
A letter denoting the
type of orbital,
A superscript denoting
the number of electrons
in those orbitals.
Aufbau Principle

The order in which
orbitals are filled with
electrons is known as
the Aufbau principle.
Full vs. Noble Gas
Configuration


You can use a noble
gas shell to shorten
electron
configurations.
Ex: Sodium


1s22s22p63s1
[Ne]3s1
Periodic Table


We fill orbitals in
increasing order of
energy.
Different blocks on the
periodic table (shaded
in different colors
here) correspond to
different types of
orbitals.
Periodic Table

Some
irregularities
occur when there
are enough
electrons to halffill s and d orbitals
on a given row.
Periodic Table


For instance, the
electron
configuration for
chromium is
[Ar]4s13d5 rather
than the expected
[Ar]4s23d4.
Copper is
[Ar]4s13d10.
Ionizing Transition Metals




When transition metals become ions, (Ex – Mn2+), the
electrons are lost first from the s block, rather than
the d block.
Electron configuration for Mn: [Ar]4s23d5
Electron configuration for Mn+2: [Ar]3d5
This is because the orbitals become “rearranged”
once the electrons are put in them. (Crystal Field
Theory & molecular orbitals – inorganic chemistry in
college)
AP 1989 MC #4-7
1s22s22p53s23p5
B)
1s22s22p63s23p6
C)
1s22s22p62d103s23p6
D)
1s22s22p63s23p63d5
E)
1s22s22p63s23p63d34s2
4) An impossible electron configuration
5) The ground-state configuration for the atoms of a transition
element
6) The ground-state configuration of a negative ion of a halogen
7) The ground-state configuration of a common ion of an alkaline
earth element
A)
AP 1989 MC #4-7
1s22s22p53s23p5
B)
1s22s22p63s23p6
C)
1s22s22p62d103s23p6
D)
1s22s22p63s23p63d5
E)
1s22s22p63s23p63d34s2
4) An impossible electron configuration – C (79% correct) - easy
5) The ground-state configuration for the atoms of a transition
element – E (42% correct) - medium
6) The ground-state configuration of a negative ion of a halogen – B
(62% correct) - easy
7) The ground-state configuration of a common ion of an alkaline
earth element – B (40% correct) - medium
A)
AP 1984 MC #22
1s22s22p63s23p3
Atoms of an element, X, have the electronic
configuration shown above. The compound
most likely formed with magnesium, Mg, is
 MgX
 Mg2X
 MgX2
 MgX3
 Mg3X2
AP 1984 MC #22
1s22s22p63s23p3
Atoms of an element, X, have the electronic
configuration shown above. The compound
most likely formed with magnesium, Mg, is
 MgX
 Mg2X
 MgX2
 MgX3
 Mg3X2 - 80% correct, very easy
AP 1984 MC #58
Which of the following represents the ground
state electron configuration for the Mn3+
ion? (Atomic number Mn = 25)
 1s22s22p63s23p63d4
 1s22s22p63s23p63d54s2
 1s22s22p63s23p63d24s2
 1s22s22p63s23p63d84s2
 1s22s22p63s23p63d34s1
AP 1984 MC #58
Which of the following represents the ground
state electron configuration for the Mn3+
ion? (Atomic number Mn = 25)
 1s22s22p63s23p63d4 – 32% correct - hard
 1s22s22p63s23p63d54s2
 1s22s22p63s23p63d24s2
 1s22s22p63s23p63d84s2
 1s22s22p63s23p63d34s1
HW: 6.48, 50, 52, 54, 56, 58
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This Week:

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Thursday – Gravimetric Analysis of a Chloride
Salt, Quantitative Analysis of Soluble Sulfate
Due
Friday – Electron Configurations (6.4-6.9)
10/18 – Gravimetric Analysis of a Chloride
Salt Due
10/20 – Elements Exam
10/21 – Problem Set 2 Due