Honors Chemistry
September 16, 2013
Preview of Lesson
• Where are electrons found around the
nucleus?
• 4 different shaped orbitals (x-ray diffraction
and electron microscopy)
– s, p, d, f
• Higher energy levels have more shapes
• Each orbital can hold 2 e– Locate the e- 90% of the time
• Orbital is also called Subshells
Bohr's Model
• Model of
electrons
in fixed
orbits to
explain
quantization
• Transitions
between
orbits
emits or
absorbs
light 07m07an1
Figure 6.14
Observation of unique line spectra led to
Quantum Theory
E=hν
Fourth
Third
Second
First
Nucleus
Orbital Diagrams and Electron
Configurations
• n = Principle quantum number
• Describes the energy level the electron occupies (PT)
n=4
n=3
n=2
n=1
Orbital Energy Levels
• Shape of orbital
designated by the
letters
s, p, d, f
Excited states
Ground state
Shapes of Orbitals
• Shape of orbital designated by the letters
s, p, d, f
• Orbitals have
different shapes
s Orbital shape
The s orbital has a
spherical shape
centered around
the origin of the
three axes in space.
p orbital shape
There are three dumbbell-shaped p orbitals
in each energy level above n = 1, each
assigned to its own axis (x, y and z) in space.
d orbital shapes
Things get a bit more
complicated with the five
d orbitals that are found
in the d sublevels
beginning with n = 3. To
remember the shapes,
think of “double dumbells”
…and a “dumbell
with a donut”!
Shape of f orbitals
Combination
of electron
microscopy
and x-ray
diffraction
produced
image of
orbitals
Sets of Orbitals (Subshells)
• Depending on the type of orbital, we find that they
occur in sets differing in their orientation in space
• s - set of 1
• p - set of 3
• d - set of 5
• f - set of 7
• Label P.T.
Sizes of orbitals
• Size depends on the value of n
• Orbitals with the same n are about the same
size
Check for understanding
• What is the principal quantum number for Ar?
• What are the subshells?
• How many sets of electrons are found in each
subshell?
Electron Configurations of Some Atoms
(Stop P1 + 5)
• The
first
ten
elements
1s1
1s2
1s2 2s1
1s2 2s2
1s2 2s2 2p1
1s2 2s2 2p2
1s2 2s2 2p3
1s2 2s2 2p4
1s2 2s2 2p5
1s2 2s2 2p6
Shorthand Notation for Orbitals
• Combinations of first two quantum numbers;
number of orbital types equals the shell
number (n).
• 1s
• 2s, 2p
• 3s, 3p, 3d
• 4s, 4p, 4d, 4f
• 5s, 5p, 5d, 5f, (5g)
• 6s, 6p, 6d, 6f, (6g, 6h)
Refer to electron configuration
worksheet
Agenda
• Brain Teaser
• Grade Worksheet
• Review
– Writing Electron Configuration
• Notes: Orbital Diagram
• Homework
– Short Hand Electron Configuration
– Orbital Diagram
Grade Homework
• Refer to Worksheet (Arrangement of Electrons
I)
Check for understanding (P6)
• What is the principal quantum number for Ar?
• What are the subshells?
• How many sets of electrons are found in each
subshell?
Aufbau Principle
• Aufbau Principle: start with the nucleus and
empty orbitals, then “build” up the electron
configuration using orbitals of increasing energy
Electron Configurations
• Electron Spin and Pauli Exclusion
Principle:
– Only two electrons can occupy a
single orbital and they must have
opposite spins
Electron Configurations
• Hund's Rule:
–When filling a subshell, such as the set
of 3 p orbitals, place 1 electron in each
before pairing up electrons in a single
orbital
Electron Configurations
• Arrangement of electrons in the orbitals is
called the electron configuration of the atom
• The ground state configuration can be
predicted, using the Aufbau Principle, the
Pauli Exclusion Principle, and Hund’s Rule.
Electron configurations
Filling _ rules.exe
How do we know what the filling order is?
• What chemistry tool might we rely on?
Electron Configurations and the
Periodic Table
• Valence electron configurations repeat
down a group
Ground state electron configurations
• Example: Li
– atomic number = 3
– nucleus has 3 protons
– neutral atom has 3 electrons
• 2 electrons in 1s orbital, 1 electron in 2s orbital
2s
1s
Different ways to show electron
configuration
Energy level diagram
Box notation

1s
2s

2s
1s
Spectroscopic notation
Li 1s2 2s1
Read this “one s two”
not “one s squared”
Write the superscript 1.
Don’t leave it blank
Practice
• Review (on separate sheet of paper)
– Electron Configuration
– Orbital Diagram
• Electron configuration worksheet
Using the Periodic Table
The last subshell in the electron configuration is one of these
(row #) s
(row # – 1) d
(row #) p
(row # – 2) f
The f-block is inserted into to the dblock
Electron configuration of O
• Atomic number of O = 8 so neutral atom has 8 e–
Electron configuration of Co
• Atomic number of Co = 27 so neutral atom has 27 e–
Simplifying electron configurations
• Build on the atom’s noble gas core
• He
O 1s22s22p4
O [He]2s22p4
1s2

1s

2s
  
2p
• Ar 1s22s22p63s23p6
Co 1s22s22p63s23p64s23d7
Co [Ar]4s23d7
             
1s 2s
2p
3s
3p
4s
3d

Noble Gases
• Far right of the periodic table
• These elements are extremely unreactive or
inert
• They rarely form compounds with other
elements
Noble Gas electron configurations
• What is the electron configurations for Neon
• Abbreviated way to write configurations
– Start with full outer shell then add on
• Br
• Ba
Noble Gases
• Neon- emits brilliant light when stimulated by
electricity – neon signs- 4th most abundant element in
the universe.
• Helium- light non reactive gas- used balloonsinexpensive, plentiful and harmless
• Radon- radioactive gas- can cause cancer- colorless,
odorless emitted from for certain rocks underground
Why are we doing all of this?
• Properties of atoms correlate with the
number and energy of electrons
• Electron configurations are used to
summarize the distribution of electrons
among the various orbitals
Practice
3-3 Practice
Write the complete electron
configurations and noble gas
shorthand #1-4
Practice
1. Refer to a periodic table and write the
electron configurations of these atoms.
2. Write the configurations using shorthand
notation.
• Zn
•
I
•
Cs
The f-block is inserted into to the
d-block
Find the electron configuration of
Au
• Locate Au on the periodic table
Find the electron configuration of
Au
• Au [Xe]
• The noble gas core is Xe
Find the electron configuration of
Au
• Au [Xe]6s2
• The noble gas core is Xe
• From Xe, go 2 spaces across the s-block in the 6th row  6s2
Find the electron configuration of
Au
• Au [Xe]6s24f14
• The noble gas core is Xe
• From Xe, go 2 spaces across the s-block in the 6th row  6s2
• Then detour to go 14 spaces across the f-block  4f14
– note: for the f-block, n = row – 2 = 6 – 2 = 4
Find the electron configuration of
Au
2 14
9
• Au [Xe]6s 4f 5d
• The noble gas core is Xe
• From Xe, go 2 spaces across the s-block in the 6th row  6s2
• Then detour to go 14 spaces across the f-block  4f14
– note: for the f-block, n = row – 2 = 6 – 2 = 4
• Finally go 9 spaces into the d-block on the 6th row  5d9
– note: for the d-block, n = row – 1 = 6 – 1 = 5
Electron configuration of ions
• What is an ion?
• How many electrons does Cl1- have?
– What is the electron configuration for the chloride
ion?
• How many electrons does Ca2+ have?
– What is the electron configuration for the calcium
ion?
• What do you notice?
Practice
• Draw the orbital diagram for sulfur.
– What ion does sulfur want to form and why?
• Draw the orbital diagram for Potassium.
– What ion does sulfur want to form and why?
What does this mean
• Properties of atoms correlate with the
number and energy of electrons
• Atoms like to have full outer shells.
Why is this important
Valence electrons
• Electrons in the outermost energy level
– Where all the action occurs
Practice
• Whiteboard - Atomic Structure (continued)
Team
• Write the electron configuration for silver.
• Write the noble gas configuration for silver.
• What element has the following electron configuration?
1s22s22p6 3s23p64s23d4
Today we use aspects of line
spectrum to identify elements,
compounds and mixtures?
• UV-Vis Spectrometer
– Distances and types of stars
– Blood test- carbon monoxide poisoning
– Mobile weapons detectors
– Chlorophyll
How we determine these energy
levels?