Download - Prentice-Hall 2007 General Chemistry: Chapter 9 Slide 1 of 35 Dr. Juana Mendenhall Assistant Professor Morehouse College Lecture 1 CHEMISTRY Ninth Edition

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


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


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.


Mendeleev’s Periodic Table1871

— = 44

— = 72— = 68— = 100


Periodic Law

States that the physical & chemical ppts of the elements vary with atomic number


The Periodic tableAlkali Metals

Alkaline Earths

Transition Metals

Halogens

Noble Gases

Lanthanides and Actinides

Main Group

Main Group


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


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.


Metallic Character

Increase

IncreaseIncrease in non-metallic character


Metals Tend to Lose Electrons


Nonmetals Tend to Gain Electrons


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


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


Atomic Radius

Increase

Increase


Screening and Penetration

Zeff = Z – S

Z is nuclear charge & S is the shielding constant

En = -

RH n2Zeff

2


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-


First Ionization Energy, I1

Increase

Increase


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-


First Electron Affinities


Second Electron Affinities

O(g) + e- → O-(g) EA = -141 kJ

O-(g) + e- → O2-(g) EA = +744 kJ


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.


Paramagnetism


Periodic Properties of the Elements

Download - Prentice-Hall 2007 General Chemistry: Chapter 9 Slide 1 of 35 Dr. Juana Mendenhall Assistant Professor Morehouse College Lecture 1 CHEMISTRY Ninth Edition

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