Atoms. Molecules, and Ions

Report
Chapter
2
Atoms, Molecules, and Ions
Chemistry, 4th Edition
McMurry/Fay
Dr. Paul Charlesworth
Michigan Technological University
Atomic Theory
•
Robert Boyle (1627–1691)
•
Joseph Priestley (1733–1804)
•
Antoine Lavoisier (1743–1794)
•
Joseph Proust (1754–1826)
•
John Dalton (1766-1844)
2
Robert Boyle
•
Robert Boyle (1627–
1691): Provided
evidence for the
atoms and defined the
nature of an element.
More than anyone
else, invented the
modern experimental
method.
3
Joseph Priestly
•
Joseph Priestley
(1733–1804): Isolated
oxygen gas from
decomposition of
mercury(II) oxide.
Identified 8 new gases
(more than anyone
else). Minister.
Revolutionary.
4
Antoine Lavoisier
Antoine Lavoisier
(1743–1794): Showed
that mass of products is
exactly equal to the
mass of reactants.
Father of modern
chemistry. Metric
system. Beheaded
during the revolution.
5
Conservation of Mass
6
Conservation of Mass
7
Atomic Theory
•
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.
8
Joseph Louis Proust
Joseph Louis Proust
(1754–1826): Proved
the law of definite
proportions (sometimes
called Proust’s Law).
Father was an
apothecary. Discovered
3 vegetable sugars.
9
Law of Definite Proportions
10
Atomic Theory
•
•
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
11
Dalton’s Atomic Theory
•
John Dalton (1766–
1844): Proposed
explanations for the laws
of mass conservation
and definite proportions.
Provided a unified atomic
theory. Avid
meteorologist. Worked
with Nitrous Oxide and
Nitrogen Dioxide.
12
Law of Multiple Proportions
13
Dalton’s Atomic Theory
•
John Dalton (1766–1844): Proposed explanations for the
laws of mass conservation and definite proportions.
Postulate #1
•
Elements are composed of tiny particles
called atoms
14
Dalton’s Atomic Theory
•
John Dalton (1766–1844): Proposed explanations for the
laws of mass conservation and definite proportions.
Postulate #2
•
All atoms of a given element are identical
having the element’s unique properties
15
Dalton’s Atomic Theory
•
John Dalton (1766–1844): Proposed explanations for the
laws of mass conservation and definite proportions.
Postulate #3
•
Atoms are neither created nor destroyed in
chemical reactions
16
Dalton’s Atomic Theory
•
John Dalton (1766–1844): Proposed explanations for the
laws of mass conservation and definite proportions.
Postulate #4
•
Compounds are formed when atoms of more
than one elenment combine. A given
compound always has the same relative
numbe of atoms
17
Dalton’s Atomic Theory
18
Dalton’s Atomic Theory
•
Law of Multiple Proportions:
•
When two elements form two different compounds,
the mass ratios are related by small whole
numbers.
19
Law of Multiple Proportions
20
Dalton’s Atomic Theory
•
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.
21
The Structure of Atoms
22
The Structure of Atoms
23
The Structure of Atoms
•
Cathode-Ray Tube (Thomson, 1856–1940):
•
Cathode rays
consist of tiny
negatively
charged particles,
now called
electrons.
24
The Structure of Atoms
25
The Structure of Atoms
•
•
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.
27
The Structure of Atoms
•
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.
28
The Structure of Atoms
29
The Structure of Atoms
•
Discovery of Nucleus (Rutherford, 1871 – 1937):
•
Rutherford irradiated
gold foil with a beam
of alpha () particles
to search for positive
charged particles.
30
The Structure of Atoms
31
The Structure of Atoms
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.
32
The Structure of Atoms
33
The Structure of Atoms
34
The Structure of Atoms
•
Structure of the Atom:
35
The Structure of Atoms
36
The Structure of Atoms
Atomic Mass Unit
1 amu =
1/12 of the mass of on atom of
Carbon-12
1 amu = 1.6605 x 10-24 g
37
The Structure of Atoms
•
Isotopes: Atoms with identical atomic numbers, but
different mass numbers.
•
Atomic Mass: A weighted average of the isotopic
masses of an element’s naturally occurring
isotopes.
38
The Structure of Atoms
•
The isotope
75
34Se
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.
39
The Structure of Atoms
•
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?
40
The Structure of Atoms
41
Compounds and Mixtures
42
Ions
•
Electrically charged atom or group of atoms
Cation:
• Anion:
•
•
(+) charge
(-) charge
Ionic Compound: A compound that consists of ions
43
Ions
44
Ions
45
Atoms, Molecules, and Ions
46
Atoms, Molecules, and Ions
47
Naming Cations
1. Elements having just one characteristic ionic
charge
Simply use the name of the element:
Na+ sodium ion
K+
potassium ion
Ca2+ calcium ion
Zn2+
Al3+
etc.
zinc ion
aluminum ion
48
Naming Cations
2. Elements forming more than one type of cation
Follow the name of the element with its stock
number (Roman numeral equal to the number of
electrons lost):
Fe2+ iron (II) ion
Fe3+ iron (III) ion
Pb2+ lead (II) ion
Pb4+ lead (IV) ion
49
Naming Anions
Stem + ide
FClBrO2S2N3-
fluoride
chloride
bromide
oxide
sulfide
nitride
50
Naming Oxoanions
Stem + ate
If more than one combination exits:
Stem + ate → larger number of O atoms
Stem + ite → smaller number of O atoms
51
Some Common Oxoanions
(NO3)(NO2)(SO4)2(SO3)2(PO4)3(CO3)2OH-
nitrate
nitrite
sulfate
sulfite
phosphate
carbonate
hydroxide
52
Some Common Oxoanions
Dichromate
(Cr2O7)2-
Permanganate
(MnO4)-
Hydrogen Carbonate
(HCO3)-
Bromate
(BrO3)-
Chlorate
(ClO3)-
53
Polyatomic Ions
54
Ionic Compounds
•
Ionic Bonding (Ionic Solids): These are formed by
a transfer of one or more electrons from one atom
to another.
55
Ionic Compounds
•
Which of the following drawings represents an ionic
compound, and which a molecular compound?
56
Ionic Compounds
•
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.
57
Naming Ionic Compounds
Combine Ion Names
Cation + Anion
NaCl
CuCl
CuCl2
CaCO3
Al2O3
sodium chloride
copper (I) chloride
copper (II) chloride
calcium carbonate
aluminum oxide
58
Naming Ionic Compounds
•
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
59
Common Oxoacids
60
Molecules
•
Covalent Bonding (Molecules): The most
common type of chemical bond is formed when two
atoms share some of their electrons.
61
Molecules
62
Molecules and Compounds
•
Molecule: A definite and distinct group of bonded
atoms
•
Molecular compound: A compound consisting of
molecules
•
Molecular formula:
•
Molecular Weight (MW): The average mass of
one of the molecules of a compound.
Water → H20
63
Naming Molecular Compounds
MUCH more complicated!
Binary compounds are often named as if they were
ionic:
HCl
CO2
hydrogen chloride
carbon dioxide
64
The Alkanes
65
The Alkanes
66
Other Interesting Compounds
67
Other Interesting Compounds
68

similar documents