Advanced Higher Chemistry

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Advanced Higher Chemistry
Unit 1 Electronic Structure and the Periodic Table
Topic 1.2 Electronic configuration
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What is in elements?
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Delving inside
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History of Quantum theory
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Erwin Schrödinger wave-mechanical
theory. Integrated quantum mechanics, the wave
view of an electron, and the exclusion principle,
producing wave equations, that predict a region
of high probability in which an electron can be
found.
Main points in his theory
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• The fixed orbit levels of an electron are
  regions where the electron waves amplify each
  other instead of cancelling in the particle
  view, they are the only permitted energy levels.

• Each wave function defines one allowed energy
  level.

• Four variables are necessary to solve the wave
  equation n, l, ml, and ms. These values are
  called quantum numbers, and together they define
  one energy state only certain values for each
  number are allowed.

The first three specify the orbital's location in
space, while the third specifies which electron
the equation describes.
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n principle quantum number
how far away from the nucleus the electron shell
under consideration is
The larger the value of n, the farther away the
shell is since shells are concentric, farther
shells are also larger. n can have any
whole-number value greater than zero, but any
number bigger than about 4 is uncommon (all the
electrons in the largest atoms can fit into about
this many shells).
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l angular momentum quantum number
the shape of the subshell (each electron shell
except n1 is composed of several subshells).
The maximum number of subshells in any electron
shell is equal to n - 1 for instance, the 3rd
electron shell has permissible l values of 0, 1,
and 2. Before the quantum number system was
instituted, subshells were referred to with
letters 0 was s, 1 was p, 2 was d, 3 was f, 4
was g, and so on. Many texts will still use the
"s-p-d-f..." system, so be sure you understand
how the letters and l values correspond.
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ml magnetic quantum number
which orbital an electron belongs to
Orbitals in a subshell but differ in their
orientation- one might point "up," another to the
"left," etc. Possible orbital values range from
the negative value of l through zero to the
positive value of l. For instance, possible ml
values for an l value of 3 are -3, -2, -1, 0, 1,
2, and 3.
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ms spin quantum number
Two electrons are possible for each orbital, the
ms value is necessary to fulfill the exclusion
principle.
Possible values for this number at 1/2 or
-1/2. If only one electron occupies an orbital,
the electron may have either value (the
assignment is arbitrary, since this number serves
only to separate the electrons).
Using these four quantum numbers, n, l, ml, and
ms you can precisely describe any electron in any
element.
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Quantum atoms
Summary- atomic structure is firmly based on the
nonrelativistic quantum theory. This theory is
capable of describing the electronic structure of
the elements and all of modern chemistry. The
wave functions can be visualised as these
diagrams show.
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Activity- collect cards Principles
Match the names of the theories with their
definitions These are the ones you need to know
about for AH.
Activity- Watch the dvd Atom episode 1
Pupil Handout- Quantum numbers
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Orbitals
Show the areas of probability that electrons are
found in
s-orbitals
Wave function Electron density Dots Radial
distribution Equations (Shrodinger)
Activity- Visit the Orbitron
http//winter.group.shef.ac.uk/orbitron/AOs/1s/ind
ex.html
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p-orbitals
Orientated along the geometrical axes, x- y- and
z.
2p
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d-orbitals
Much more complex orientations. On the axes (zx,
yz and xy) and between axes (z2 and x2-y2)
3d
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f-orbitals
Just for completeness, you dont need to know any
more about them for this course!
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Electronic configuration
This describes the order in which orbitals fill
Notice anything about the order of filling?
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Orbital box notation
Some of the possible orbitals starting at 1s and
going up to 3d
Electrons can be described in a chemical
shorthand using two main methods

• Spectroscopic notation

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Linking to the periodic table
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Webstuff
Activities- check out the website
http//www.chemguide.co.uk/atoms/properties/elstru
cts.htmltop
Writing electronic structure in spectroscopic
notation
And
http//library.thinkquest.org/C004970/atoms/index.
htm
Relevant sections for this topic are

• Electromagnetic Radiation
• Historical Concepts of Atoms
• Spectrum Lines and Ionization Energies
• Quantum Theory, the Uncertainty Principle, and
  Pauli's Exclusion Principle
• Electron Orbitals, Quantum Numbers, and Orbital
  Filling

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Ionisation enthalpies
Revise your Higher Chemistry Trends and patterns
in the PT inc. ionisation enthalpies
Pupil Activity
Use your data book and Excel to graph out the
ionisation enthalpies for the first 20 elements
in the periodic table
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Scholar work
Topic 2 Electronic configuration and the periodic
table
2.1 Introduction 2.2 Spectra, quanta and
ionisation 2.3 Quantum numbers 2.4 Atomic
orbitals 2.5 Orbital shapes 2.6 Electronic
configurations 2.7 Writing orbital box
notation 2.8 Ionisation energy 2.9 Summary 2.10
Resources 2.11 End of Topic 2 test