Transcript Chapter 1: Matter and Measurement

Petrucci • Harwood • Herring • Madura
GENERAL
CHEMISTRY
Ninth
Edition
Principles and Modern Applications
Chapter 9: The Periodic Table and
Some Atomic Properties
Dr. Juana Mendenhall
Assistant Professor
Morehouse College
Lecture 1
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Objectives
1
2
3
4
5
Define and locate periods, groups, families, and
transition elements on the periodic table
Define & explain metals and nonmetals and their ions
Define atomic size and indicate factors that influence
atomic size, such as covalent, ionic, metallic, and van
der Waals radii
1 Indicate the trends that affect atomic size using
the periodic table
Define and indicate ionization energy and relate trends
using the periodic table
Define electron affinity & relate trends to the periodic
table
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Classifying the Elements: The Periodic
Law and the Periodic Table
1869, Dimitri Mendeleev
Lother Meyer
When the elements are arranged in order
of increasing atomic mass, certain sets of
properties recur periodically.
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Mendeleev’s Periodic Table
1871
—
= 44
—
= 68
—
= 72
—=
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Periodic Law
States that the physical & chemical ppts of the elements vary with atomic
number
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Alkali Metals
The Periodic table
Alkaline Earths
Halogens
Noble Gases
Main Group
Transition Metals
Main Group
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Lanthanides and Actinides
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Trends in electron configurations
Group 1A
Li
[He]2s1
Group 2A
Valence electrons: outer electrons
of an atom
Be
[He]2s2
Mg
[Ne]3s2
Ca
[Ar]4s2
Na
[Ne]3s1
K
[Ar]4s1
Rb
[Kr]5s1
Sr
[Kr]5s2
Cs
[Xe]6s1
Ba
[Xe]6s2
Fr
[Rn]7s1
Ra
[Rn]7s2
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that are involved
in chemical bonding
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Metals and Nonmetals and Their Ions
Metals
 Good conductors of heat and electricity.
 Malleable and ductile.
 Moderate to high melting points.
Nonmetals
 Nonconductors of heat and electricity.
 Brittle solids.
 Some are gases at room temperature.
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Metallic Character
Increase
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Increase
Increase in
non-metallic character
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Metals Tend to Lose Electrons
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Nonmetals Tend to Gain Electrons
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Electron Configurations of Cations and Anionsof
Some Ions
Cations
Anions
Na [Ne]3s1
Na+ [Ne]
H 1s1
H- 1s2
Ca[Ar]4s2
Ca2+[Ar]
F 1s22s22p5
F- 1s22s22p6
Al[Ne]3s23p1 Al3+ [Ne]
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Sizes of Atoms and Ions
Physical properties such as density, melting point,
and boiling point are related to size of atoms.
Atomic radius: is one-half the distance b/w the
two nuclei in two adjacent metal atoms;
elements that exist as diatomic molecules the atomic
radius is one-half the distance b/w the nuclei of the
two atoms in a particular molecule
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Atomic Radius
Increase
Increase
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Screening and Penetration
Zeff = Z – S
Z is nuclear charge &
S is the shielding
constant
Zeff2
RH 2
n
En = Slide 15 of 35
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Ionization Energy
Ionization energy: measures how strongly an atom hold its electrons.
Ioniziation energy is the minimum energy required to remove an electron
from the ground state of the isolated gaseous atom.
First Ionization energy, I1, is the energy needed to remove the first e-
Mg(g) → Mg+(g) + e-
I1 = 738 kJ
Second Ionization energy, I2, is the energy needed to remove the second
electron
Mg+(g) → Mg2+(g) + e-
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I2 = 1451 kJ
2
Z
I = RH eff
n2
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First Ionization Energy, I1
Increase
Increase
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Electron Affinity
Measures the energy change (attraction or affinity) that occurs when
an electron is accepted by atom in the gaseous state.
F(g) + e- → F-(g)
EA = -328 kJ
F(1s22s22p5) + e- → F-(1s22s22p6)
Li(g) + e- → Li-(g)
EA = -59.6 kJ
We assign a (-) value to the electron affinity when energy is released.
The more (-) the EA, the greater the tendency the atom can accept an eSlide 18 of 35
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First Electron Affinities
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Second Electron Affinities
O(g) + e- → O-(g)
EA = -141 kJ
O-(g) + e- → O2-(g)
EA = +744 kJ
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Magnetic Properties
Diamagnetic atoms or ions:
 All e- are paired.
 Weakly repelled by a magnetic field.
Paramagnetic atoms or ions:
 Unpaired e-.
 Attracted to an external magnetic field.
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Paramagnetism
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Periodic Properties of the Elements
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General Chemistry: Chapter 9
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