Download Atoms. Molecules, and Ions

Chapter
2
Atoms, Molecules, and Ions
Chemistry, 4th Edition
McMurry/Fay
Dr. Paul Charlesworth
Michigan Technological University
Conservation of Mass
Prentice Hall ©2004
Chapter 02
Slide 2
Dalton’s Atomic Theory
01
•
Robert Boyle (1627–1691): Provided evidence for
the atoms and defined the nature of an element.
•
Joseph Priestley (1733–1804): Isolated oxygen
gas from decomposition of mercury(II) oxide.
•
Antoine Lavoisier (1743–1794): Showed that
mass of products is exactly equal to the mass of
reactants.
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Chapter 02
Slide 3
Dalton’s Atomic Theory
•
02
Law of Mass Conservation: Mass is neither
created nor destroyed in chemical reactions.
•
Law of Definite Proportions: Different samples of
a pure chemical substance always contain the
same proportion of elements by mass.
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Chapter 02
Slide 4
Dalton’s Atomic Theory
•
03
John Dalton (1766–1844): Proposed explanations
for the laws of mass conservation and definite
proportions.
Flash Animation - Click to Continue
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Chapter 02
Slide 5
Dalton’s Atomic Theory
Prentice Hall ©2004
Chapter 02
04
Slide 6
Dalton’s Atomic Theory
04
•
Law of Multiple Proportions:
•
When two elements form two different compounds,
the mass ratios are related by small whole
numbers.
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Chapter 02
Slide 7
Dalton’s Atomic Theory
•
•
05
Nitrogen & oxygen combine to form NO or NO2:
•
In NO the N:O mass ratio is 7:8
•
In NO2 the N:O mass ratio is 7:16
Hydrogen & oxygen combine to form H2O or H2O2:
•
In H2O the H:O mass ratio is 1:8
•
In H2O2 the H:O mass ratio is 1:16
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Chapter 02
Slide 8
Dalton’s Atomic Theory
•
06
Methane and ethane are both constituents of
natural gas. A sample of methane contains 11.40 g
of carbon and 3.80 g of hydrogen, whereas a
sample of ethane contains 4.47 g of carbon and
1.118 g of hydrogen. Show that the two substances
obey the law of multiple proportions.
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Chapter 02
Slide 9
The Structure of Atoms
•
Cathode-Ray Tube (Thomson, 1856–1940):
•
Cathode rays
consist of tiny
negatively
charged particles,
now called
electrons.
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Chapter 02
01
Slide 10
The Structure of Atoms
•
•
02
Deflection of electron depends on three factors:
•
Strength of electric or magnetic field
•
Size of negative charge on electron
•
Mass of the electron
Thomson calculated the electron’s charge to mass
ratio as 1.758820 x 108 Coulombs per gram.
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Chapter 02
Slide 11
The Structure of Atoms
03
•
Oil Drop Experiment (Millikan, 1868–1953): Applied a voltage
to oppose the downward fall of charged drops and suspend
them.
•
Voltage on plates place
1.602176 x 10-19 C of
charge on each oil drop.
•
Millikan calculated the
electron’s mass as
9.109382 x 10-28 grams.
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Chapter 02
Slide 12
The Structure of Atoms
05
•
Discovery of Nucleus (Rutherford, 1871 – 1937):
•
Rutherford irradiated
gold foil with a beam
of alpha () particles
to search for positive
charged particles.
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Chapter 02
Slide 13
The Structure of Atoms
05
Discovery of Nucleus (Rutherford, 1871–1937):
Rutherford irradiated
gold foil with a beam
of alpha () particles
to search for positive
charged particles.
Atom must be mostly
empty space except
for a central positive
mass concentration.
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Chapter 02
Slide 14
The Structure of Atoms
•
04
Structure of the Atom:
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Chapter 02
Slide 15
The Structure of Atoms
Prentice Hall ©2004
Chapter 02
05
Slide 16
The Structure of Atoms
06
•
Isotopes: Atoms with identical atomic numbers, but
different mass numbers.
•
Average Isotopic Mass: A weighted average of
the isotopic masses of an element’s naturally
occurring isotopes.
•
Atomic Mass: A weighted average of the isotopic
masses of an element’s naturally occurring
isotopes.
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Chapter 02
Slide 17
The Structure of Atoms
•
The isotope
75
34Se
07
is used medically for diagnosis of
pancreatic disorders. How many protons, neutrons,
and electrons does an atom of
•
75
34Se
have?
An atom of element X contains 47 protons and 62
neutrons. Identify the element, and write the
symbol for the isotope in the standard format.
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Chapter 02
Slide 18
The Structure of Atoms
•
08
Chlorine has two naturally occurring isotopes: 35
17 Cl
with an abundance of 75.77% and an isotopic mass
of 34.969 amu, and
37
17 Cl
with an abundance of
24.23% and an isotopic mass of 36.966 amu. What
is the atomic mass of chlorine?
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Chapter 02
Slide 19
Compounds and Mixtures
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Chapter 02
01
Slide 20
Compounds and Mixtures
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Chapter 02
02
Slide 21
Atoms, Molecules, and Ions
•
01
Covalent Bonding (Molecules): The most
common type of chemical bond is formed when two
atoms share some of their electrons.
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Chapter 02
Slide 22
Atoms, Molecules, and Ions
•
02
Ionic Bonding (Ionic Solids): These are formed by
a transfer of one or more electrons from one atom
to another.
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Chapter 02
Slide 23
Atoms, Molecules, and Ions
•
03
Which of the following drawings represents an ionic
compound, and which a molecular compound?
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Chapter 02
Slide 24
Atoms, Molecules, and Ions
04
•
Naming Binary Ionic Compounds:
•
Identify the positive ion and then the negative ion.
•
The positive ion uses its elemental name.
•
The negative ion substitutes the second half of its
elemental name with –ide.
•
Do not use Greek prefixes such as mono–, di–, or
tri–.
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Chapter 02
Slide 25
Atoms, Molecules, and Ions
Prentice Hall ©2004
Chapter 02
05
Slide 26
Atoms, Molecules, and Ions
Prentice Hall ©2004
Chapter 02
06
Slide 27
Atoms, Molecules, and Ions
•
07
Main Group Cations and Anions.
Ions combine to form neutral compounds.
Examples:
Na+ and Cl– combine to form NaCl.
Ca2+ and Cl– combine to form CaCl2.
Al3+ and Cl– combine to form AlCl3.
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Chapter 02
Slide 28
Atoms, Molecules, and Ions
Prentice Hall ©2004
Chapter 02
08
Slide 29
Atoms, Molecules, and Ions
09
Naming Binary Molecular Compounds:
• The more cationlike element uses its elemental
name.
•
•
The more anionlike element substitutes the second
half of its elemental name with –ide.
•
Use the Greek prefixes to express the number of
each element present.
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Chapter 02
Slide 30
Atoms, Molecules, and Ions
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Chapter 02
10
Slide 31
Atoms, Molecules, and Ions
•
11
If the green spheres represent cations, and the
blue represent anions, which of the formulas are
consistent with the figure?
(a) LiBr
(b) NaNO2
(c) CaCl2
(d) K2CO3
(e) Fe2(SO4)3
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Chapter 02
Slide 32
Atoms, Molecules, and Ions
Prentice Hall ©2004
Chapter 02
12
Slide 33
Atoms, Molecules, and Ions
•
13
Name the following acids:
(a) HBrO(aq)
(b) HCN(aq)
(c) HIO4(aq)
(d) HBrO2(aq)
(e) H2CrO4(aq)
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Chapter 02
Slide 34