 # Chapter 6 Electronic Structure and Periodicity. Objectives Periodic law Organization of the periodic table Electromagnetic Radiation (added) Quantum mechanics.

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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  Distance between Measured in

Radiant Energy Frequency ( ) –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 -7 m?

Practice 2 What is the wavelength of light that has a frequency of 2.88 x 10 17 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

Line Spectrum 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 10 16 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 ShellNumber (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 HEREHERE 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

Orbitals Each 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

P z orbital

P y orbital

P x 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/orbi tron/index.htmlhttp://www.shef.ac.uk/chemistry/orbi tron/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 HEREHERE

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 filling is from the bottom (low energy) up –Due to energy levels

Rules for Orbital Filling Diagonal Rule The 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 12 C: 32 S:

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

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