Post on 04-Jan-2016
Chapter 6
Electronic Structure and
Periodicity
Objectives
• Periodic law• Organization of the periodic table• Electromagnetic Radiation (added)• Quantum mechanics• Periodic Trends
Periodic Table
• Label appropriately…• Properties of elements
– Know the trends…• Explained by organization in atom
– Electronic structure
Electromagnetic Radiation
• Electromagnetic spectrum• Radio waves cosmic rays• Visible light is small portion
Radiant Energy• WAVES– Light travels in
• Light is a form of
– E.R. is a form of
Radiant Energy• All waves can be described in 4
ways:– Amplitude
•
Radiant Energy• Wavelength ( )l
• Distance between
• Measured in
Radiant Energy• Frequency (n)
– Number of
– Measured in
Radiant Energy• Speed
– Speed of light in air is – Electromagnetic radiation moves
through a vacuum at a speed
– Represented by ‘c’
As in c =
Radiant Energy• Since light moves at a constant
speed there is a relationship between wavelength and frequency
Practice
• What is the frequency of light if the wavelength is 4.65 x 10-7m?
Practice 2
• What is the wavelength of light that has a frequency of 2.88 x 1017 s-1?
Radiant Energy• Electromagnetic Spectrum
– Includes all – Visible spectrum
• • What we can see•
• Note Electromagnetic spectrum, identifying key areas (wavelength, frequency)
Electromagnetic Spectrum
Model of the Atom
• Niels Bohr• • Explains
The Bohr Atom• Model didn’t seem to work
• Did not explain
• Bohr’s Proposed Model:– The single electron of the hydrogen atom can
circle the nucleus only in
– The location of the electron(s) in each orbit determines a
– The orbit closest to
– Potential Energy increases
– Each orbit (energy level)
Another Look at the Atom
First Law of Thermodynamics
• Energy is • Energy in
• Bohr Model Animation
Another Look at the Atom
Emission Spectra
• Radiation emitted by an
• Color is • Fireworks
LineSpectrum
• Elements in gaseous states
– High temperature or high voltage
– Always
– Each element is •
Line Spectrum• Ground state
– • Excited state
–
– Farther – Higher
Line Spectrum• Electron
• Color of light
Line Spectrum• Each band of color is produced by
light of a different • Each particular wavelength has a
definite
• Each line must therefore be produced by
Beginnings…• Max Planck (1858-1947)
– Proposed that there is a fundamental restriction on the amounts of energy that an object emits or absorbs, and he called each of these pieces of energy a
• Energy is released in
Beginnings• A quantum is a finite quantity of energy
that can be gained or lost by an atom
•
Practice• Determine the energy of light that has a
frequency of 3.5 x 1016 s-1
Quantum Theory
Schroedinger, Einstein, Planck…etc…
Another Look at the Atom
• Quantum Theory describes mathematically the
• This model applies to
Terms…• Electron shell:
A region of space
There are Corresponds to the Can hold
Shells and Electrons
Shell Number (n) Electron Capacity
Terms…• Electron subshell
A region of space within a
There are the same number of
Terms• Orbital – a 3-dimensional region
– A bit more specific than • The sizes and shapes of the electron
clouds
• An individual electron cannot be pinpointed – Heisenberg’s Uncertainty Principle
Terms…• Probability and Orbitals
– Electron cloud is
– Figure 6.8 and 6.9 pg 194• Learn the rules and quantum
numbers and then put it all together…
Quantum numbers• Numbers that specify the properties of
atomic orbitals and their electrons– A system of – A method of giving – Tell you how the – Schroedinger figured this out using BIG math– If you’re curious… go HERE
• There are 4
Principal Quantum Number• The first • Energy level –
• Corresponds to the
• Value of • Symbolized by n
Azimuthal Quantum Number
• The second quantum number• Tells you the
• Usually shown as
OrbitalsEach subshell (orbital) has a specific shape
http://daugerresearch.com/orbitals/
Quantum Numbers• Orbital (azimuthal) Quantum Number:
– Indicates the – (subshell or sublevels)– Principal Quantum # Orbital Quantum #
1 2 3 4
Magnetic Quantum Number
• The third number• Tells you
• • Has values of +l to -l
S orbital
Pz orbital
Py orbital
Px orbital
D orbital
S, P, D orbitals
F orbital
Orbitron
• For a full view of the different orbital shapes, visit
• http://www.shef.ac.uk/chemistry/orbitron/index.html
Spin Quantum Number• Final quantum number• Tells you in which
• Electrons behave like little
• Value of + or – ½ or…• If you’re curious… go HERE
Putting it all together
• Table 2.6 and 2.7• Orbital arrangement on the periodic
table• Electron configuration• Aufbau principal
– “Building up’
Pauli Exclusion Principal
• No more than
• No electron can
Hund’s Rule
• Electrons will fill empty orbitals before they
• Applies to • Electrons (little magnets)
Rules for Orbital Filling• Pauli’s Exclusion Rule
– No two electrons
• Hund’s Rule
1s 2s 2p 3s 3p
Rules for Orbital Filling• Aufbau
– The order of fillingis from the
bottom (low energy) up
– Due to energy levels
Rules for Orbital Filling
Diagonal RuleThe order of filling
once the d & f sublevels are being filled
Due to energy levels
4f
Alternates…
Application of Quantum Numbers
• Several ways of writing the
• Lowest energy levels are • Electron Configuration: using the diagonal
rule, the principal quantum number (n), and the sublevel write out the location of all electrons
12C: 32S:
Definitions of Configurations• Electron Configuration
– Uses principle and orbital quantum numbers, superscript for electrons
• Orbital-filling Electron Diagram– Uses Hund’s Rule– Show electrons with
• Electron Dot Diagram– Shows ONLY the OUTER SHELL electrons
• Chemical Symbol represents the nucleus and all other electrons
• Use dots for outer shell electrons