Transcript Chapter 1: Matter and Measurement

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Chemistry 140 Fall 2002 Dutton
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Things To Remember
A= mass number
Particle
Electron
Proton
Neutron
Mass
kg (SI)
9.109 x 10-31
1.673 x 10-27
1.675 x 10-27
Z = atomic number
amu
0.000548
1.00073
1.00087
Chemistry 140 Fall 2002 Dutton
Charge
Coulombs (SI)
–1.602 x 10-19
+1.602 x 10-19
0
(e)
–1
+1
0
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Alkali Metals
The Periodic Table
Alkaline Earths
Halogens
Noble Gases
Main Group
Transition Metals
Main Group
Lanthanides and Actinides
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The Periodic Table
•
•
•
•
Read atomic masses.
Read the ions formed by main group elements.
Read the electron configuration.
Learn trends in physical and chemical properties.
We will discuss these in detail in Chapter 10.
Chemistry 140 Fall 2002 Dutton
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The Mole
• Physically counting atoms is impossible.
• We must be able to relate measured mass to
numbers of atoms. Similar to:
–
–
–
–
buying nails by the pound.
buying eggs by the dozen.
buying beer by the case.
using atoms by the gram.
Chemistry 140 Fall 2002 Dutton
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Avogadro’s Number
The mole is an amount of substance that
contains the same number of elementary
entities as there are carbon-12 atoms in
exactly 12 g of carbon-12.
NA = 6.02214199 x 1023 mol-1
NA = 602214199000000000000000 mol-1
Chemistry 140 Fall 2002 Dutton
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Molar Mass
• The molar mass, M, is the mass of one mole
of a substance. Mass of one
atom of 12C
M (g/mol 12C) = A (g/atom 12C) x NA (atoms 12C /mol 12C)
• The molar mass of an atom is the atomic
weight of that element in units of gmol-1.
• The molar mass of a molecule is the
addition of the atomic weights of all atoms
making up the molecule in units of gmol-1.
Chemistry 140 Fall 2002 Dutton
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Example 2-9
Combining Several Factors in a Calculation—Molar Mass, the
Avogadro Constant, Percent Abundance.
Potassium-40 (40K) is one of the few naturally occurring
radioactive isotopes of elements of low atomic number. Its
percent natural abundance among K isotopes is 0.012%. How
many 40K atoms do you ingest by drinking one cup of whole
milk containing 371 mg of K?
Want atoms of 40K, need atoms of K,
Want atoms of K, need moles of K,
Want moles of K, need mass and M(K).
Chemistry 140 Fall 2002 Dutton
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Useful Formula’s
Calculating Numbers of
Particles
Calculating Numbers of
Moles
N = n x NA
n=m/M
N = number of particles
NA = Avogadro’s number
(particles / mol)
n = number of moles (mol)
n = number of moles (mol)
m = mass (g)
M = molar mass (g / mol)
Chemistry 140 Fall 2002 Dutton
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Strategies (Flowchart)
m=nxM
n = N / NA
Number of
Particles
Mass of
Substance
Moles
N = n x NA
N = n x NA
n=m/M
n=m/M
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Convert Strategy to Plan
and Plan Into Action
n=m/M
Convert mass of K(mg K) into moles of K (mol K)
mK(mg) x (1g/1000mg)  mK (g) x 1/MK (mol/g)  nK(mol)
nK = (371 mg K) x (10-3 g/mg) x (1 mol K) / (39.10 g K)
= 9.49 x 10-3 mol K
Convert moles of K into atoms of 40K
N = n x NA
nK(mol) x NA  atoms K x 0.012%  atoms 40K
atoms 40K = (9.49 x 10-3 mol K) x (6.022 x 1023 atoms K/mol K)
x (1.2 x 10-4 40K/K)
= 6.9 x 1017 40K atoms
Chemistry 140 Fall 2002 Dutton
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Chapter 2 Questions
3, 4, 5, 9, 11,
21, 22, 24, 25,
33, 51, 55, 63,
65, 83.
Chemistry 140 Fall 2002 Dutton
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General Chemistry
Principles and Modern Applications
Petrucci • Harwood • Herring
8th Edition
Chapter 3: Chemical Compounds
Philip Dutton
University of Windsor, Canada
N9B 3P4
Prentice-Hall © 2002
(modified 2003 by Dr. Paul Root and 2005 by Dr. David Tramontozzi)
Chemistry 140 Fall 2002 Dutton
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Contents
3-1
3-2
3-3
3-4
Molecular and Ionic Compounds
Molecular Mass
Composition
Oxidation States
3-5
Names and formulas
Focus on Mass Spectrometry
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Molecular Compounds
 Molecular Compound, discrete units of molecules.
 Chemical formula, symbolic representation of compound
showing numbers and types of atoms.
Simplest formula of compound
Actual formula of compound
Actual attachment of atoms
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Standard Color Scheme
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Some Molecules
H2O2
CH3CH2Cl
CH3CH(OH)CH3
P4O10
HCO2H
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Condensed
Structural
Formulas
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Ionic Compounds
 Atoms of almost all elements can gain or lose electrons to
form charged species called ions.
 Compounds composed of ions are known as ionic compounds.
 Metals tend to lose electrons (lose negative
charge) to form positively charged ions called
cations.
Non-metals tend to gain electrons (gain
negative charge) to form negatively charged
ions called anions.
Chemistry 140 Fall 2002 Dutton
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Sodium chloride (Table Salt)
Extended array of Na+ and Cl- ions.
FORMULA
UNIT
Formula Unit, smallest
electrically neutral
collection of ions. Smallest
whole number ratio giving a
neutral ionic compound.
Ball and stick crystal arrangement
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Space filling arrangement
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Inorganic Molecules
P4
S8
 Some inorganic molecules are made of clusters of identical atoms.
 Need to be familiar with the difference between atomic mass and molecular mass.
Chemistry 140 Fall 2002 Dutton
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