prentice-hall 2007 general chemistry: chapter 9 slide 1 of 35 dr. juana mendenhall assistant...
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Prentice-Hall © 2007 General Chemistry: Chapter 9 Slide 3 of 35 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.TRANSCRIPT
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 1 of 35
Dr. Juana Mendenhall Assistant ProfessorMorehouse College
Lecture 1
CHEMISTRYNinth
Edition GENERALPrinciples and Modern Applications
Petrucci • Harwood • Herring • Madura
Chapter 9: The Periodic Table and Some Atomic Properties
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 2 of 35
Objectives1 Define and locate periods, groups, families, and transition
elements on the periodic table2 Define & explain metals and nonmetals and their ions3 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
4 Define and indicate ionization energy and relate trends using the periodic table
5 Define electron affinity & relate trends to the periodic table
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 3 of 35
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.
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 4 of 35
Mendeleev’s Periodic Table1871
— = 44
— = 72— = 68— = 100
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 5 of 35
Periodic Law
States that the physical & chemical ppts of the elements vary with atomic number
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 6 of 35
The Periodic tableAlkali Metals
Alkaline Earths
Transition Metals
Halogens
Noble Gases
Lanthanides and Actinides
Main Group
Main Group
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 7 of 35
Trends in electron configurations
Group 1A
Li [He]2s1
Na [Ne]3s1
K [Ar]4s1
Rb [Kr]5s1
Cs [Xe]6s1
Fr [Rn]7s1
Group 2A
Be [He]2s2
Mg [Ne]3s2
Ca [Ar]4s2
Sr [Kr]5s2
Ba [Xe]6s2
Ra [Rn]7s2
Valence electrons: outer electrons
of an atom
that are involved
in chemical bonding
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 8 of 35
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.
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 9 of 35
Metallic Character
Increase
IncreaseIncrease in non-metallic character
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Metals Tend to Lose Electrons
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Nonmetals Tend to Gain Electrons
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 12 of 35
Electron Configurations of Cations and Anionsof Some Ions
Cations
Na [Ne]3s1 Na+ [Ne]
Ca[Ar]4s2 Ca2+[Ar]
Al[Ne]3s23p1 Al3+ [Ne]
Anions
H 1s1 H- 1s2
F 1s22s22p5 F- 1s22s22p6
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 13 of 35
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
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 15 of 35
Screening and Penetration
Zeff = Z – S
Z is nuclear charge & S is the shielding constant
En = -
RH n2Zeff
2
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 16 of 35
Ionization Energy
Mg(g) → Mg+(g) + e- I1 = 738 kJSecond Ionization energy, I2, is the energy needed to remove the
second electron
Mg+(g) → Mg2+(g) + e- I2 = 1451 kJ
I = RHn2
Zeff2
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-
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 17 of 35
First Ionization Energy, I1
Increase
Increase
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 18 of 35
Electron Affinity
F(g) + e- → F-(g) EA = -328 kJ
F(1s22s22p5) + e- → F-(1s22s22p6)
Li(g) + e- → Li-(g) EA = -59.6 kJ
Measures the energy change (attraction or affinity) that occurs when
an electron is accepted by atom in the gaseous state.
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 e-
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 19 of 35
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
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 21 of 35
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.
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 22 of 35
Paramagnetism
Prentice-Hall © 2007General Chemistry: Chapter 9Slide 23 of 35
Periodic Properties of the Elements