QUIZ Clear off your area except for a calculator and penpencil

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Announcements General Info
QUIZ! Clear off your area except for a
calculator and pen/pencil Atomic Spectra Lab
Report Due Periodic Trends Lab Thursday Will
assign trends at the beginning of class No
pre-lab due Lab report sheet due at the end of
class Lecture cover most of Chapter 8
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Atoms with more than one Electron

• For an atom with many electrons, what orbitals
  are used?
• Need to introduce 4th quantum number, ms,the spin
  quantum number.
• Spin
• ms can have values of 1/2

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Atoms with more than one Electron (contd.)

• Pauli Exclusion Principle
• This means that each orbital can contain 2
  electrons.
• Aufbau rule
• Remember, for H atom, only n determined energy
  for many electron atoms, l is a factor also.

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Factors Affecting Atomic Orbital Energies

• The energy of an orbital is measured by how easy
  it can be removed
• An electron is stabilized by interaction with the
  nucleus, which depends on nuclear charge (Z) and
  distance (Coulombs Law).

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Factors Affecting Atomic Orbital Energies (contd.)

• Electrons in inner orbitals shield outer
  electrons, causing them to feel less of a
  charge from the nucleus (Zeffective lt Z).

• Energy of an orbital depends on its distance from
  the nucleus (probability of finding electron near
  nucleus). s orbital radial distribution diagram
  has a peak very close to the nucleus.
• Leads to general order of energies

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The Effect of Other Electrons on Inner Orbitals
Zeff lt 3
Zeff 3
Figure 8.5
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Order for filling energy sublevels with electrons
Figure 8.7
Illustrating Orbital Occupancies
The electron configuration

of electrons in the sublevel
n
l
The orbital diagram (box or circle)
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Figure 8.8
no color-empty
A vertical orbital diagram for the Li ground state
light - half-filled
dark - filled, spin-paired
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Electron Configurations for 2nd Period (Li ? Ne)
1s22s1
Be
1s22s2
B
1s22s22p1
C
1s22s22p2
1s22s22p3
N
O
1s22s22p4
1s22s22p5
F
Ne
1s22s22p6
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Electron Configurations
s orbitals hold up to electrons p orbitals hold
up to electrons d orbitals hold up to
electrons f orbitals hold up to electrons

of electrons in the sublevel
l
n
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Ground State Versus Excited State
When an electron is excited, it jumps to a HIGHER
energy orbital. An excited electron is NOT an
electron that is gained or lost . An excited
element 1s22s22p63s23p34s1 The 3p orbital can
hold up to 6 electrons. This electron
configuration means that an electron from the 3p
orbital jumped to the 4s orbital. Sum the
superscripts to determine total of electrons
Full ground-state electron configuration C
ondensed ground-state electron configuration
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The Electronic Configuration of Ions

• When an electron is removed from an atom to give
  a cation, the __________ energy electron is
  removed.
• e.g. Na 1s22s22p63s1 ? Na 1s22s22p6
• Na is isoelectronic with Ne
• When an electron is added to give an anion, the
  electron is added to the __________ energy shell
• e.g. F 1s22s2 2p5 ? F 1s22s2 2p6
• F is isoelectronic with Ne

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Hunds Rule

• If there is more than one orbital with the same
  energy, electrons will partially occupy empty
  orbitals, before they pair up to fill an
  orbital. This is Hunds rule.
• A substance with one or more unpaired spins is
• Diamagnetic substances

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(No Transcript)
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• Exception Cr is Ar4s13d5 rather than
  Ar4s23d4
• Half full 3d level happens to be especially
  stable.

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• Exception Cu is Ar4s13d10 rather than
  Ar4s23d9 (full 3d level is especially stable)

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Figure 8.13
The relation between orbital filling and the
periodic table
Need to memorize the order of orbital
filling! green box
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Size of Ions vs Atoms

• Cations are __________ than the corresponding
  neutral atoms
• Less electronelectron repulsion. Valence
  electrons can more strongly interact with the
  nucleus.
• For the same atom, increasing positive charge
  makes the ion smaller (M2 smaller than M).
• Anions are __________than the neutral atoms
• More e e repulsions, electrons spread out
• Thus, for isoelectronic ions, anions will be much
  larger than cations.
• Metallic Properties
• Metals
• Non-metals

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Transition Metal Cations

• Transition metals possess filled ns orbitals (n
  4, 5, 6) and partially filled (n1)d orbitals.
• When transition metals form cations, the
  electrons are sometimes removed from the ns
  rather than the (n1)d orbitals the s orbitals
  have become higher in energy than the d orbitals.
• e.g. configuration of Ti Ar4s23d2 Ti
  Ar4s13d2 Ti2 Ar3d2
• For some transition metals, it is difficult to
  rank the ionization energy because you do not
  know from which orbital the electron is being
  removed. You will NOT have to deal with
  transition metal cations on the quizzes or the
  exams.

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Periodic Properties Web Exercise

• Thursday we will explore four properties of
  elements to see how they vary across the periodic
  table, either down a group or across a period.
  The properties are
• (1) Ionization energy
• (2) Electron affinity
• (3) Atomic radius
• (4) Ionic radius

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Definitions
Effective Nuclear Charge Shielding Core (or
Inner) Electrons Electrons that fill all the
energy levels for an atom except the valence
level. Valence Electrons The electrons of an
atom in the outer-most orbital level.
Isoelectronic Elements