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HSTMr.Watson
Chapter 8Chapter 8
Electron Configuration and Periodicity
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OrbitalsOrbitals
region of probability of finding an electron around the nucleus
4 types => s p d fmaximum of 2 electrons per orbital
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Pure Atomic OrbitalsPure Atomic Orbitals
shape # of orbitals / energy level
s spherical 1
p dumbbell 3
d complex 5
f very complex 7
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Pauli Exclusion PrinciplePauli Exclusion Principle
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Electronic ConfigurationsElectronic Configurations
The shorthand representation of the occupancy of the energy levels (shells and subshells) of an atom by electrons.
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Electronic ConfigurationElectronic Configuration
shells => energy levels
subshells => orbitals
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Regions by Electron TypeRegions by Electron Type
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Electron Filling Order Electron Filling Order DiagramDiagram
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d
7s
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Electronic ConfigurationElectronic Configuration
H atom
1 electron
1s1
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Electronic ConfigurationElectronic Configuration
He atom
2 electrons
1s2
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Electronic ConfigurationElectronic Configuration
Li atom
3 electrons
1s2, 2s1
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Electronic ConfigurationElectronic Configuration
Cl atom
17 electrons
1s2, 2s2, 2p6, 3s2, 3p5
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Electronic ConfigurationElectronic Configuration
As atom
33 electons
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p3
or
[Ar] 4s2, 3d10, 4p3
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Mn: [Ar]4s2 3d?
How many d electrons does Mn have?
4, 5, 6
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Electronic ConfigurationElectronic Configuration
negative ions
add electron(s), 1 electron for each negative charge
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Electronic ConfigurationElectronic Configuration
S-2 ion
(16 + 2)electrons
1s2, 2s2, 2p6, 3s2, 3p6
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Electronic ConfigurationElectronic Configuration
positive ions
remove electron(s), 1 electron for each positive charge
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Electronic ConfigurationElectronic Configuration
Mg+2 ion
(12-2)electrons
1s2, 2s2, 2p6
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How many valence electrons are in Cl, [Ne]3s2 3p5?
2, 5, 7
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For Cl to achieve a noble gas configuration, it is more likely that
electrons would be added
electrons would be removed
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Trends in theTrends in thePeriodic TablePeriodic Table
atomic radiusionic radiusionization energyelectron affinity
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Atomic RadiusAtomic Radiusdecrease left to right across a period
– as nuclear charge increases, number of electrons increase; however, the nucleus acts as a unit charge while the electrons act independently, pulling electrons towards the nucleus, decreasing size
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Atomic RadiusAtomic Radiusincrease top to bottom down a group
– each additional electron “shell” shields the outer electrons from the nuclear charge
Zeff = Z - Swhere Zeff => effective nuclear charge
Z => nuclear charge, atomic numberS => shielding constant
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Atomic RadiusAtomic Radiusincreases from upper right corner to the
lower left corner
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Atomic Radius vs. Atomic Number
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Atomic RadiusAtomic Radius
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Ionic RadiusIonic Radiussame trends as for atomic radiuspositive ions smaller than atomnegative ions larger than atom
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Ionic RadiusIonic Radius
Isoelectronic Seriesseries of negative ions, noble gas atom, and
positive ions with the same electronic confiuration
size decreases as “positive charge” of the nucleus increases
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Ge is a semiconductor. If half of the Ge atoms of a sample of Ge are replaced with Ga atoms, with what element should the other half of the Ga atoms be replaced in order for this new compound to be isoelectronic with Ge?
Sn, As, Se
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Ionization EnergyIonization Energyenergy necessary to remove an electron to
form a positive ionlow value for metals, electrons easily
removedhigh value for non-metals, electrons
difficult to removeincreases from lower left corner of periodic
table to the upper right corner
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Ionization EnergiesIonization Energies
first ionization energyenergy to remove first electron from an
atom
second ionization energyenergy to remove second electron from a +1
ion
etc.
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Ionization Energy vs. Atomic NumberIonization Energy vs. Atomic Number
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Electron AffinityElectron Affinity
energy released when an electron is added to an atom
same trends as ionization energy, increases from lower left corner to the upper right corner
metals have low “EA”nonmetals have high “EA”
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MagnetismMagnetism
Result of the spin of electronsdiamagnetism - no unpaired electronsparamagnetism - one or more unpaired
electronsferromagentism - case of paramagnetism
where the substance retains its magnetism
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MagnetismMagnetism
Paramagnetism
Ferromagnetism
Without applied field Without applied field
With applied fieldWith applied field
