Atoms, Atoms Everywhere Electron Configuration

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Atoms, Atoms Everywhere!Electron Configuration
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Orbitals, not Orbits!

• The Heisenberg Uncertainty Principle says -
  loosely - you can't know with certainty both
  where an electron is and where it's going next.
  That makes it impossible to plot an orbit for an
  electron around a nucleus. But we can imagine
  orbitals!

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Characteristics of Orbitals

• 95 of the time (or any percentage you choose),
  an electron will be found within a fairly easily
  defined region of space quite close to the
  nucleus called an orbital.
• Note If you wanted to be absolutely 100 sure of
  where the electron is, you would have to draw an
  orbital the size of the Universe!

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Characteristics of Orbitals

• What is the electron doing in the orbital? We
  don't know! All we know is an electron in a
  particular orbital has a definable energy.
• Each orbital has a name. For example in 1s
  orbital the "1" means the orbital is in the
  energy level closest to the nucleus while "s"
  tells you the shape of the orbital.

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The 1s Orbital

• If you kept plotting the location of a single
  electron at a certain point in time over and
  over, youd gradually build up a 3D map of the
  places the electron is likely to be found.
• Hydrogens electron, for example, can be found
  anywhere within a spherical space surrounding the
  nucleus (the 1-s orbital).

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The 2s Orbital

• Similar to a 1s orbital except thatthe region
  where there is the greatest chance of finding the
  electron is further from the nucleus - this is an
  orbital at the second energy level.
• If you look carefully, you will notice that there
  is another region of slightly higher electron
  density (where the dots are thicker) nearer the
  nucleus.

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3s, 4s, etc. Orbitals

• 3s, 4s (etc) orbitals get progressively further
  from the nucleus.
• 2s (and 3s, 4s, etc) electrons do spend some of
  their time close to the nucleus. Which slightly
  reduces the energy of electrons in s orbitals.
  The nearer the nucleus the electrons get, the
  lower their energy.

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2p or not 2pGood Question!

• Not all electrons inhabit s-orbitals (in fact,
  very few electrons live in s-orbitals).
• At the first energy level, electrons can only
  choose a 1s orbital, but at the second energy
  level they can choose 2p orbitals, too.

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p Orbitals are not Pointless

• The p-orbital still shows where there is a 95
  chance of finding a particular electron, but
  p-orbitals point in a particular direction.
• At any one energy level it is possible to have
  three absolutely equivalent p-orbitals oriented
  at right angles.

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Beyond the 2p Orbitals

• The p-orbitals at the second energy level are
  called 2px, 2py and 2pz. There are similar
  orbitals at higher levels - 3px, 3py, 3pz, 4px,
  4py, 4pz and so on.
• All levels except for the first level have
  p-orbitals. At the higher levels the lobes get
  more elongated, with the most likely place to
  find the electron more distant from the nucleus.

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d- and f- Orbitals

• There are two other sets of orbitals which become
  available for electrons to inhabit at higher
  energy levels.
• At the third level, there is a set of five d
  orbitals (with complicated shapes and names) for
  a total of nine orbitals.
• At the fourth level, there are an additional
  seven f orbitals - 16 orbitals in all.

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Mental Health Break!
Too many orbitals! Too many orbitals!
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So Lets Fill Some Orbitals!

• This is the order of increasing energy for
  atomic orbitals.
• (Lowest) 1s lt 2s lt 2p lt 3s lt 3p lt4s lt 3d lt4p lt
  5s lt 4d lt 5p lt 6s lt 4f lt 5d lt 6p lt 7s lt 5f lt 6d
  lt 7p lt 8s ...(Highest).
• Fill from lowest energy oribital to highest!

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Same Idea Using Pictures
NOTE 4s orbital fills before 3d orbitals. The
same thing happens at the next level as well -
the 5s orbital fills before the 4d orbitals.
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Of Course, There are Rules!

• Pauli Exclusion Principle
• Hunds Rule
• The Aufbau Process

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Pauli Exclusion Principle

• Suggests that only two electrons with opposite
  spin can occupy an atomic orbital.
• The idea is that orbitals (energy states) have
  limited room to accommodate electrons.

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Hunds Rule

• Electrons prefer parallel spins in separate
  orbitals of subshells.
• In other words, single electrons fill each and
  all orbitals in the subshell before they pair up
  with electrons with opposite spins.

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The Aufbau Process

• The Aufbau Procedure (filling order of atomic
  orbitals) is used to work out the electron
  configurations of all atoms.
• The Aufbau Procedure is based ona rough energy
  levels diagram of many-electron atoms shown on
  the next slide

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Orbital Energy Diagrams
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Lets Try a Few!

• http//lectureonline.cl.msu.edu/mmp/period/electr
  on.htm
• http//intro.chem.okstate.edu/WorkshopFolder/Elect
  ronconfnew.html

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Writing Them Out

• B 1s22s22px1
• C 1s22s22px12py1
• N 1s22s22px12py12pz1
• O 1s22s22px22py12pz1
• F 1s22s22px22py22pz1
• Ne 1s22s22px22py22pz2

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Orbitals and the Periodic Table
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Why Name em s, p, d, f?

• The names are left over from 19th century
  spectroscopy (everyone uses it, so we're stuck
  with it.)
• s stands for "sharp,"
• p is for "principal
• d is for "diffuse
• f is for "fundamental

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Time To Practice It All!