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Periodicity
• 7. Atomic Structure and Periodicity
7.1 Electromagnetic Radiation
7.2 The Nature of Matter
7.3 The Atomic Spectrum of Hydrogen
7.4 The Bohr Model
7.5 The Quantum Mechanical Model of the Atom
7.6 Quantum Numbers
7.7 Orbital Shapes and Energies
7.8 Electron Spin and the Pauli Principle
7.9 Polyelectronic Atoms
7.10 The History of the Periodic Table
7.11 The Aufbau Principles and the Periodic Table
7.12 Periodic Trends in Atomic Properties
7.13 The Properties of a Group: The Alkali Metals
Dr. Ron Rusay
Fall 2007
© Copyright 2002-2007 R.J. Rusay
Periodic Table
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• Mendeleev’
Mendeleev’s Table 1868-1871
Mural at St.Petersburg University, Russia
© Copyright 1998-2007 R.J. Rusay
Periodic Properties
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Periodic Trends
Atomic Radius
Atomic Radii
Atomic Radii:
Radii:
What’
What’s a picometer?
picometer?
1 x 10 -12 m
decreases going from left to right
across a period;
period;
increases going down a group.
group.
Ionization Energy
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Ionization Energy
The quantity of energy required to
remove an electron from the gaseous
atom or ion.
QUESTION
The first ionization energy of Mg is 735 kJ/mol.
The second ionization energy is:
1) 735 kJ/mol.
2) less than 735 kJ/mol.
3) greater than 735 kJ/mol.
4) More information is needed to answer this
question.
5) none of these.
What is the charge of a common magnesium ion? Explain.
Periodic Trends
First ionization energy:
energy:
increases from left to right
across a Period;
Period;
decreases going down a
Group.
Group.
QUESTION
Choose the element with the highest IE.
1) Na
2) Mg
3) Al
4) P
5) S
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QUESTION
Which of the following atoms would have the
largest second ionization energy?
1) Mg
2) Cl
3) S
4) Ca
5) Na
Electron Affinity
The energy change associated
with the addition of an electron to a
gaseous atom.
atom.
X(g) + e− → X−(g)
Electronegativity
1A 2A 3A 4A 5A 6A 7A 8A
(1) (2) (13) (14) (15) (16) (17) (18)
Electronegativity
First ionization
Energy (kJ/mol)
Atomic radius (pm)
1A
2A 3A
(1)
(2) (13) (14) (15) (16) (17) (18)
4A 5A 6A 7A
8A
1A 2A 3A 4A 5A 6A 7A 8A
(1) (2) (13) (14) (15) (16) (17) (18)
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Trends in Reactivity
Lithium (Li), Sodium (Na) & Potassium (K)
What is trend in the
chemical reactivity
observed for the
alkali metals, Group
IA?
•What might account for this trend?
•Do you expect the Alkaline Earths
(Group IIA) to behave similarly?
•Does this trend apply to all Groups?
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Transition Metals
(B Group Elements)
Transition Metals (B Groups)
Oxidation States
Radii of
B Group Elements
Information & the Periodic Table
A great deal of specific, general and comparative
information can be developed from the Periodic
Table:
1. Group valence electron configurations.
2. Individual electron configurations.
3. General chemical behavior and
physical properties.
4. Distinguishing metals and nonmetals.
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Summary of Periodic Trends
Summary of Periodic Trends
Periods (Horizontal Rows)
Periods (Horizontal Rows)
Atomic size generally decreases across a
Period.
The first ionization energy and
electronegativity generally increase across
a Period..
This is a result of increasing effective nuclear
charge and electrons being in the same
principal energy level.
Metallic character decreases as
elements change from metals to
metalloids to nonmetals.
General reactivity is highest at the left
and right ends of a Period. (Excluding
the inert noble gases.)
In Period 2, the physical properties
change abruptly between carbon (solid)
and nitrogen (gas).
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