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 ModelBohr's Model
• Model ofelectronsin fixedorbits to explain quantization Figure 6.14
• Transitionsbetweenorbitsemits orabsorbslight 07m07an107m07an1
07m07an1.mov.lnk
Observation of unique line spectra led to Quantum Theory
Nucleus
First
Second
Third
FourthE=hν
Orbital Diagrams and Electron Configurations
• n = Principle quantum number • Describes the energy level the electron occupies (PT)
n = 1
n = 2n = 3n = 4
Orbital Energy Levels
Ground stateGround state
Excited statesExcited states
• Shape of orbitaldesignated by theletters
s, p, d, f
Shapes of OrbitalsShapes of Orbitals• Shape of orbital designated by the letters
s, p, d, f• Orbitals have
different shapes
The s orbital has a spherical shape centered aroundthe origin of the three axes in space.
s Orbital shapes 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.
p orbital shapep orbital shape
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”!
d orbital d orbital shapesshapes
Shape of f orbitalsShape of f orbitals
CombinationCombination
of electronof electron
microscopymicroscopy
and x-rayand x-ray
diffractiondiffraction
producedproduced
image ofimage of
orbitalsorbitals
Sets of Orbitals (Subshells)Sets of Orbitals (Subshells)
• Depending on the type of orbital, we find that they occur in sets differing in their orientationsets differing in their orientation in space in space
• s - set of 1• p - set of 3• d - set of 5 • f - set of 7
• Label P.T.
Orbitals.exe.lnk
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)
Electron Configurations of Some Atoms(Stop P1 + 5)
• The firstten 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 OrbitalsShorthand 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
Aufbau.exe
Electron ConfigurationsElectron 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 configurationsElectron configurations Filling _ rules.exeFilling _ rules.exe
How do we know what the filling order is?
• What chemistry tool might we rely on?
Electron Configurations and the Periodic Table
Electron Configurations and the Periodic Table
• Valence electron configurations repeat down a group
aufbau.exe.lnk
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
1s
2s
Different ways to show electron configuration
Read this “one s two”not “one s squared”
1s
2s
1s 2s
Li 1s2 2s1
Energy level diagram Box notation
Spectroscopic notation
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 d-block
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 1s2
O 1s22s22p4
O [He]2s22p4
• Ar 1s22s22p63s23p6
Co 1s22s22p63s23p64s23d7
Co [Ar]4s23d7
1s 2s 2p
3s 3p
4s 3d
1s 2s 2p
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 balloons- inexpensive, plentiful and harmless
• Radon- radioactive gas- can cause cancer- colorless, odorless emitted from for certain rocks underground
• 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
Why are we doing all of this?Why are we doing all of this?
PracticePractice
3-3 PracticeWrite 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
• Au [Xe]6s24f145d9
• 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?