What is Chemistry

1
Chapter 2 Atoms, Molecules and Ions

• What is Chemistry

Logic
Magic
Chapt. 2.1
2
Atoms, Molecules and Ions

• Science Atomic Theory
• The strength of a science is that its
  conclusions are derived by logical arguments from
  facts that result from well-designed experiments.
  Science has produced a picture of the
  microscopic structure of the atom so detailed and
  subtle of something so far removed from our
  immediate experience that it is difficult to see
  how its many features were constructed. This is
  because so many experiments have contributed to
  our ideas about the atom.
• B. Mahan
  from University Chemistry

Chapt. 2.1
3
Atoms, Molecules and Ions

• Science Atomic Theory
• from a fundamental understanding of the
  macroscopic behavior of substances comes an
  understanding the microscopic behavior of atoms
  and molecules (Baseball rules from Baseball Game?)

Macroscopic Microscopic Substances
Atomic theory Mixtures Physical
Properties and Changes
Question Can matter be infinitely divided?
Most Greek Philosophers - Yes Democritus (460
BC) and John Dalton (1800s) - No (atomosmeans
indivisible)
Chapt. 2.1
4
Atoms, Molecules and Ions

• History of Atomic Theory and Scientific Inquiry
• Aristotle - metaphysics, thought
  experiments and no experimental
  observations necessary to substantiate ideas.
• Archimedes (287 - 212 BC) - Scientific Method,
  determined composition of the King of Syracuses
  crown by measuring density through water
  displacement.
• Roger Bacon (1214 - 1294) - Experimental
  Science It is the credo of free men - the
  opportunity to try, the privilege to err, the
  courage to experiment anew. ...experiment,
  experiment, ever experiment.

Chapt. 2.1
5
Archimedes (287-212BC)

• Archimedes was a native of Syracuse (not NY).
  Stories from Plutarch, Livy, and others describe
  machines invented by Archimedes for the defence
  of Syracuse (These include the catapult, the
  compound pulley and a burning-mirror).
• Archimedes discovered fundamental theorems
  concerning the centre of gravity of plane figures
  and solids. His most famous theorem gives the
  weight of a body immersed in a liquid, called
  Archimedes' principal.

• His methods anticipated integral calculus 2,000
  years before Newton and Leibniz.

6
Archimedes (287-212BC)
7
Archimedes (287-212BC)
Suspecting that a goldsmith might have replaced
some of the gold by silver in making a crown,
Hiero II, the king of Syracuse, asked Archimedes
to determine whether the wreath was pure gold.
The wreath could not be harmed since it was a
holy object. The solution which occurred when he
stepped into his bath and caused it to overflow
was to put a weight of gold equal to the crown,
and known to be pure, into a bowl which was
filled with water to the brim. Then the gold
would be removed and the king's crown put in, in
its place. An alloy of lighter silver would
increase the bulk of the crown and cause the bowl
to overflow.
Equal Weight of Gold
Pure Gold?
Crown Displaced More Water
8
Greek Philosophers
Air
Fire
Greek Elements
Water
Earth

• Democratus - First to say that all matter is
  NOT infinately divisible. But the Greeks
  did not test their ideas
• Alchemy - Pseudoscience by fakes and mystics
  devoted to turning base metals to gold BUT they
  did make (by accident) many ground breaking
  discoveries of nature (chemical reactions).

9
Scientific Measurement

• Robert Boyle - Robert Boyle (1627-1691)
  was born in Ireland. He became especially
  interested in experiments involving air and
  developed an air pump with which he
  produced evacuated cylinders. He used these
  cylinders to show that a feather and a lump
  of lead fall at the same rate in the absence
  of air resistance. In his book The Sceptical
  Chemist (1661), Boyle urged that the ancient
  view of elements as mystical substances should be
  abandoned and that an element should instead be
  defined as anything that cannot be broken down
  into simpler substances.

10
Scientific Measurement

• Antoine Lavoisier (1743 - 1794) - Furthered
  measurement as basis for scientific reasoning.
• Je Veux Parler Des Faits - Do Not Rely Upon
  Speculation But Build Upon Facts.

More on Lavoisier on Next Slide
11
Antoine Lavoisier
Antoine Lavoisier was born in Paris,
and although Lavoisier's father wanted him
to be a lawyer, Lavoisier was
fascinated by science. From the
beginning of his scientific career,
Lavoisier recognized the importance of
accurate measurements. He wrote the first modern
chemistry (1789) textbook so that it is not
surprising that Lavoisier is often called the
father of modern chemistry. To help support his
scientific work, Lavoisier invested in a private
tax-collecting firm and married the daughter of
one of the company executives. Guillotined for
his tax work in 1794.
12
Atoms, Molecules and Ions
Earth

• History Atomic Theory and Scientific Inquiry
• Lavoisier (1743 - 1794) - founder of modern
  chemistry, not to rely on speculation but to
  build upon facts, ended the time of alchemy.

Alchemy
Fire
Water
earth
pure water
evaporate out water from dust sealed container
alchemists said that the water was transmuted
to earth
Law of Conservation of Mass
Lavoisier showed that the amount of earth found
at the end of the experiment was equal to the
weight the container lost, therefore, the water
was not transmuted to earth.
Chapt. 2.1
13
Scientific Method
Form and test hypothesis
Patterns and Trends
Theory
Observations and Experiments
Chapt. 2.1
14
John Dalton (1766-1844)
John Dalton (1766 -1844), an Englishman,
began teaching school when he was 12. He was
fascinated with meteorology (keeping daily
weather records for 46 years), which led
to an interest in gases and their components,
atoms. He switched to chemistry when he saw
applications in chemistry for his ideas about the
atmosphere. He proposed the Atomic Theory in
1803. Dalton was a humble man with several
apparent handicaps he was poor he was not
articulate he was not a skilled experimentalist,
and he was color-blind (a terrible problem for a
chemist). In spite of these disadvantages he did
great things.
15
Atomic Theory

• John Daltons Atomic Theory
• Designed a theory to account for a variety of
  experimental observations
• Each element is composed of extremely small
  particles (called atoms).
• All atoms of a given element are identical
  (therefore, atoms of different elements are
  different and have different properties).

Chapt. 2.1
16
Atomic Theory (Continued)

• John Daltons Atomic Theory
• Atoms of an element are not changed into
  different types of atoms by chemical reactions
  and atoms are neither created nor destroyed in
  chemical reactions.
• Compounds are formed when atoms combine and a
  given compound always has the same relative
  number and kind of atoms.

Chapt. 2.1
17
Atomic Theory

• Daltons Atomic Theory
• Atoms are the building blocks
• Elements are composed of only one kind of atom.
• Compounds are made by mixing atoms in definite
  proportions
• Mixtures do not involve the type of small scale
  (but strong) interactions found in Elements and
  Compounds

Chapt. 2.1
18
Atomic Theory Daltons Theories

• Law of Constant Composition (or Definite
  Proportion, first proposed by Joseph Proust)
• In any given compound, the relative number and
  kind of atoms are constant (same proportion of
  elements by mass).
• implies that atoms interact in a specific way
  when they form a compound.
• the elements making up a particular compound
  combine in the same proportions regardless of the
  manner in which the compound was prepared.

Chapt. 2.1
19
Atomic Theory Daltons Theories

• Law of Constant Composition (or Definite
  Proportion)

Copper Carbonate ALWAYS contains 5.3 parts Copper
to 4 parts Oxygen and 1 part Carbon (by
Weight). Carbon Dioxide ALWAYS contains 1.00
parts Carbon to 2.67 parts Oxygen
Chapt. 2.1
20
Atomic Theory Daltons Theories

• Law of Conservation of Mass
• the total amount of material present after a
  chemical reaction is the same as the amount
  present before the reaction.

Matter (elements, etc...) cannot be created nor
destroyed during chemical reactions.
Total Mass Before Chemical Reaction
Total Mass After Chemical Reaction

Chapt. 2.1
21
Guy-Lussac

• Joseph Guy-Lussac (1778 - 1850) found that (at
  the same temperatures and pressures)
• 2 volumes of hydrogen reacts with 1 volume of
  oxygen to yield 1 volume of water vapor

Water
O
H
Amedeo Avogadro (1776 - 1856) proposed that (at
the same temperatures and pressures), equal
volumes of different gases contain the same
number of particles
2 molecules of H 1 molecule of O yield 1
molecule of water
22
Experiments in Atomic Theory
Daltons Laws Set Groundwork for Atomic Theory
but Important Experiments Lead to Our Modern
Understanding

• Faraday - Electrodeposition
• Millikan - Oil Drop Experiment
• Roetgen - Radioactivity
• Curie - Radioactive Particles
• Rutherford - Gold Foil Experiment

23
Michael Faraday (1791-1867)
Experiments in electro-magnetism, electrical
power conversion, etc... Humble scientist rose
from very poor background to become one of the
most influential of his age. Believed that
careful observations were most important. Try
desperately to succeed - and do not hope for
success
24
Atomic Structure

• Electrical Nature
• Michael Faraday (1833) (first ideas about the
  nature of electricity
• The weight of a material deposited at an
  electrode by a given amount of electricity is
  always the same.
• The weights of various materials deposited by
  fixed amounts of electricity are proportional to
  their equivalent weights. remember equivalent
  weights

Chapt. 2.1
25
Sir J. J. Thomson
British physicist who worked with electrical
currents and fields. Appointed Prof. of Physics
at Cambridge when he was 27 and Received the
Nobel Proze in 1906 for his characterization
of the electron.
26
Atomic Structure

• J. J. Thomson Cathode Ray Tube (CRT) Experiment
• Set up a large electrical potential between a
  pair of electrodes in a glass tube and an
  electrical current will flow between the
  elctrodes.
• The current will flow even when all the air is
  pumped out of the tube. The invisible charge
  carriers were called cathode rays.
• Cathode rays travel in straight lines and form a
  luminious spot when they hit a glass tube.

(-)
()
Cathode Ray Tube evacuated glass tube
Chapt. 2.1
27
Atomic Structure CRT
The cathode rays are deflected by an electric
field.
(-)
()
Electric Field
The cathode rays are deflected by an magnetic
field.
(-)
()
The same effect was observed regardless of what
gas was used in the discharge tube. Therefore,
electricity must be a universal fragment.
Magnetic Field
Chapt. 2.1
28
Electricity Thomsons charge to mass
(-)
CRT
()
1 2 3
(-)
()
Magnetic Field
Electric Field
Spot mag field elec. field 1 On
Off 3 Off On 2 Off Off On On
Chapt. 2.1
29
Thomsons charge to mass
Ee Electrical Field He? Magnetic
Field where e electric charge (unk) and ?
velocity Set up experiment such that Electrical
Field Magnetic Field Ee He? or ????E /
H Now, turn off the mag. field and measure
deflection of beam (?) Using Newtons 2nd Law can
calculate e/m
(-)
CRT
()
1 2 3
(-)
()
Magnetic Field
30
Thomsons charge to mass

• calculated charge to mass ratio (e/m)
• for electron 1.76 x 108 coulombs/g
• found
• (1) e/m was 1000x greater than for any known ion
• (2) e/m of independent of gas in tube Universal
  Fragment
• (3) Not electrified atoms but fragments (called
  electrons)

31
Robert Millikan (1868-1953)
Nobel Prize, 1923 for his work on the
elementary charge of electricity and on the
photoelectric effect. Robert Millikan was
one of the first American scientists to be
recognized in Europe. In 1909 he
performed the first of a series of
experiments to measure the fundamental
charge of an electron, the Millikan Oil Drop
Experiment. The value determined by this
experiment was used in Bohr's formula for the
energy of the Hydrogen line spectrum as a first
confirmation of the quantized atom. He named
and studied "cosmic rays" as well.
32
Electricity Millikans electron mass
Oil Drop Experiment (1909)

• Goal to measure the electrical charge on each
  oil droplet
• Procedure measure the velocity of the falling
  oil drop both with and without the high voltage
  plates urned on
• Found charges were always multiples of 1.60 x
  10-19 C
• Postulate charge of one electron was 1.60 x
  10-19 C

atomizer
-
high voltage
viewer

Ionization by radiation causes the oil to pick up
extra electrons
Chapt. 2.1
33
Electricity electron mass
charge e 1.76 x 108 coul g-1 mass
m
charge e 1.60 x 10-19 coul
Combine and Solve
mass charge 1.60 x 10-19
C 9.10 x 10-28 g 1.76 x 108
coul g-1 1.76 x 108 C g-1

• mass of the electron was 2000x smaller than the
• lightest atom (hydrogen)

Chapt. 2.1
34
Wilhelm Conrad Roentgen
Wilhelm Conrad Roentgen was born in Lennep,
Germany, on 27 March 1845. He obtained a degree
in mechanical engineering and, in 1869, was
awarded a degree in physics. While working as a
professor of physics at Wurzburg University, he
made his famous discovery. He called the unknown
radiation "X rays," since "X" frequently stands
for an unknown quantity in mathematics. His
unique discovery truly changed the world and
immediately became a useful tool for medical
science.
Wilhelm Conrad Roentgen
35
Radioactivity Wilhelm Roetgen and Henri Becquerel
metal target
CRT
e beam

• X-rays
• - not affected by magnetic fields
• - passed thru many materials
• -produced images on film
• (ionized Ag emulsions)

invisible radiation (X-rays)
glowed in dark (phosphorescence)
emitted high energy radiation in the dark
(radioactivity)
Chapt. 2.1
36
1903 Nobel Prize for Radioactivity
Pierre and Marie Curie
Henri Becquerel
37
Marie Sklodawaska Curie
The most famous of all women scientists, Marie
Sklodowska-Curie is notable for many firsts. In
1903, she became the first woman to win a
Nobel Prize for Physics (Pierre Curie and Henri
Becquerel, for the discovery of
radioactivity. She was also a professor at the
Sorbonne University in Paris (1906). In 1911,
she won an unprecedented second Nobel Prize (in
chemistry for her discovery radium. She was
the first person ever to receive two Nobel
Prizes.) She was the first mother of a Nobel
Prize Laureate daughter- Nobel Prize 1932.
Marie Sklodowska-Curie In 1934, Maria Curie died
of leukemia
38
Radioactivity Marie Curie and Ernest Rutheford

• Marie Curie (1867 - 1934) - separated the pure
  radioactive material (Uranium) which was
  spontaneously radioactive (from the mineral
  pitchblende)
• Ernest Rutheford (1871 - 1937) - found radiation
  from uranium was of three types (?, ?, and ?)

?
-
?

slits
?
? - heavy particles with 2 charge, combines with
electrons to form helium, 4He ? - electrons with
-1 charge ? - high energy electromagnetic
radiation
Chapt. 2.1
39
Nuclear Atom Thomsons Model (ca. 1900)

• Since the electron made up only a small amount of
  an atoms mass it was proposed that it must
  similarly make up a small amount of the atoms
  volume.

Plum-pudding model
positive charge spread over sphere
electron
40
Ernest Rutherford
Ernest Rutherford (1871-1937) was born on
a farm in New Zealand. In 1895 he placed
second in a scholarship competition to
attend Cambridge University, but was
awarded the scholarship when the winner
decided to stay home and get married. As a
scientist in England, Rutherford did much of
the early work on characterizing
radioactivity. He also invented the name
proton for the nucleus of the hydrogen atom. He
received the Nobel Prize in chemistry in 1908.
41
Nuclear Atom Rutheford and the Gold Foil

• experiment - fired
• heavy ? particles
• at a thin gold foil
• and looked
• for deflections

?
?
4He particles
thin gold foil
slits
detector
found - most particles passed straight through
foil, some had deflections thru small angles BUT
some had VERY large deflections (? 180)
...as if you fired a 15-inch cannon shell at a
piece of tissue paper and it came back and hit
you...
42
Nuclear Atom Rutheford and the Gold Foil
Gold Foil
AC around 13,0001
A
? Beam
A
C
B
B
A
A
43
Ruthefords Atom

• Based on gold foil experiment and previous work
  with electrical and nuclear particles, proposed a
  nuclear theory
• (1) atoms are mostly empty space with very dense
  (pos. charged) nuclear core (lt10-12 cm dia.)
• (2) atoms are highly non-uniform
• (3 ) atomic nucleus must contain large electrical
  forces of considerable mass (since small electron
  cannot be responsible for such large deflections)

44
Natures Basic Forces

• Electromagnetic - force between charged or
  magnetic particles (electrical and magnetic
  forces are very closely related). DRIVES
  MOST OF CHEMICAL BEHAVIOR (Coulombs Law F
  kQ1Q2/d2)
• Gravitational - force between objects
  proportional to their masses.
• Strong Nuclear - force keeping like charged
  nucleons (such as protons) together (very
  strong but very short range).
• Weak Nuclear - nuclear force observed in some
  radioactive behavior (weaker than electromagnetic
  but stronger than gravitational).

-
m
m
Strong Nucl. gt Electromagnetic gt Weak Nucl. gt
Gravitational
45
Modern Atomic Structure

• atomic dimensions nucleus 10-4 Å and atom 1 - 2
  Å (1 Å 10-10 m) ... if a nucleus were 2 cm
  (ca. 1 in.) then the atom would be 200 m (ca.
  200 yds)
• atom composed of many subatomic particles but
  only three of these are important to chemists
• atomic mass (1 amu 4 x 10-22 g), charge (1
  esc 1.60 x 10-19 coul), density (1014 g/cm3)
• atom dense nucleus with mostly empty space
  electrons of most chemical import. (matchbox of
  nucl. 2.5 billion tons)

particle charge (esu) mass (amu) proton 1 1.007
3 neutron 0 1.0087 electron -1 5.486 x 10-4
46
Atomic Theory Isotopes

• differences/similarities between atoms of an
  element
• all atoms of an given element have the same
  number of protons (and therefore the same number
  of electrons to balance charge)
• atoms of an element may have different numbers of
  neutrons - called isotopes

AE 11C 12C 13C 14C
Z 6 6
6 6
atomic number (Z) - number of protons mass number
(A) - number of protons number of
neutrons nuclide - atoms of a specific elemental
isotope
47
Atomic Theory Isotopes

• 7 electrons, 7 protons, 7 neutrons
• 8 electrons, 8 protons, 9 neutrons
• 17 electrons, 17 protons, 18 neutrons
• 92 electrons, 92 protons, 146 neutrons

14N
7
17O
8
35Cl
17
238U
92
48
Atomic Theory Isotopes

• Sample exerciseHow many protons, neutrons, and
  electrons are in a 39K atom?

49
Atomic Theory Isotopes

• Sample exerciseHow many protons, neutrons, and
  electrons are in a 39K atom?
• Atomic 19 of protons 19
• of electrons 19
• Mass 39 39 - 19 20 neutrons

50
Atomic Theory Isotopes

• Sample exerciseGive the complete chemical symbol
  for the nuclide that contains 18 protons, 18
  electrons, and 22 neutrons.

51
Atomic Theory Isotopes

• Sample exerciseGive the complete chemical symbol
  for the nuclide that contains 18 protons, 18
  electrons, and 22 neutrons.
• Atomic 18 , element is Argon

52
Atomic Theory Isotopes

• Sample exerciseGive the complete chemical symbol
  for the nuclide that contains 18 protons, 18
  electrons, and 22 neutrons.
• Atomic 18 , element is Argon
• 40Ar

18
53
Atomic Theory Isotopes

• Allotropes - Different chemical forms of the same
  element existing in the same physical state.

Fullerene
Graphite
Diamond
54
Periodic Table Dmitri Mendeleev (1869)

• Displays chemical reactivity trends and
  relationships and constructed to account for (and
  predict) chemical reactivity of the elements.
• For example
• Li, Na, K soft metals, v. reactive w/ water
• He, Ne, Ar gases and not reactive
• F, Cl, Br reactive with many other elements in
  a similar fashion
• Cu, Ag, Au Metal w/ similar reactivity

55
Periodic Table Dmitri Mendeleev
56
Periodic Table

• 1 Alkali metals Li, Na, K,...
• 2 Alkaline earth metals Be, Mg, Ca,...
• 16 Chalcogens (chalk formers) O, S, Se,...
• 17 Halogens (salt formers) F, Cl, Br,...
• 18 Noble Gases (inert gases) He, Ne, Ar,...

Group or Family
Row
57
Periodic Table
58
Periodic Table (1869)

• metals non-metals
• conductors insulators
• shiny dull
• high thermal conductivity thermal insulators
• solids at RT freq. non-solids at RT
• ductile brittle

Metalloids (along line in table) have properties
between metals and non-metals
59
Molecules and Ions

• Molecule - assembly of two or more atoms (with
  properties different from constituent types of
  atoms (see Law of Multiple Proportions). i.e.,
  H2O, H2O2, CaCO3, HNO3, H2SO4,...
• some elements found in nature as molecules (i.e.,
  O2, N2, etc... diatomic)
• Formulas
• Molecular - actual numbers and types of atoms in
  a molecule
• Empirical - smallest whole number ratio of
  constituentStructural - picture showing how the
  atoms are attached to one another

60
Molecules

• Molecular Empirical Structural
• Formula Formula Formula
• H2O (water) H2O
• H2O2 (hydr. peroxide) HO
• C2H4 (ethylene) CH2
• C6H12O6 (glucose) CH2O

61
Formulas

• Ethylene is a gas at room temperature and is the
  starting material for for many plastics. Its
  molecular formula is C2H4.
• What is its empirical formula?
• What other molecular formulas are possible for
  this same empirical formula?

62
Formulas

• Ethylene is a gas at room temperature and is the
  starting material for for many plastics. Its
  molecular formula is C2H4.
• What is its empirical formula?
• CH2
• What other molecular formulas are possible for
  this same empirical formula?
• C2H4 , C3H6 , C4H8 , C5H10 , ...

63
Formulas

• Cucurbituril is a compound with cage-like
  molecules big enough to surround and loosely trap
  smaller molecules. It has the molecular formula
  C36H36N24O12.
• What is its empirical formula?

64
Formulas

• Cucurbituril is a compound with cage-like
  molecules big enough to surround and loosely trap
  smaller molecules. It has the molecular formula
  C36H36N24O12.
• What is its empirical formula?
• C3H3N2O

65
Formulas

• Sample exercise Give the empirical formula for
  the substance whose molecular formula is Si2H6.

66
Formulas

• Sample exercise Give the empirical formula for
  the substance whose molecular formula is Si2H6.
• SiH3

67
Ions

• atoms can gain or lose electrons to become
  charged (called ions)
• positive ion cation negative ion anion
• Na (neutral has 11 electrons) can easily lose 1
  electron to become a cation (Na1)

68
Ions

• Polyatomic ions molecules with charges.
  i.e., NO3-1, SO4-2, PO4-3, etc...
• chemical properties of ions may be VERY different
  from similar neutral species
• Predicting charges on ions - use periodic table
  (gain or lose electrons to end up with the same
  number as the nearest noble gas)

69
Ions
1 2 -3 -2 -1
70
Ions

• Sample exercise How many protons and electrons
  does the Se2- ion possess?

71
Ions

• Sample exercise How many protons and electrons
  does the Se2- ion possess?
• Se atomic number 34
• of protons 34
• of electrons 34 2 36

72
Ionic Compounds

• transfer of electrons between atoms, Na Cl
  NaCl-
• ionic compounds contain anions and cations,
  typically combinations of metals and non-metals
  (molecular compounds, in which electrons are
  shared, are usually result from the combination
  of non-metals only) FeS, LiBr, CuSO4, TiO4,
  etc...
• total charge is neutral total () total (-)
• ionic compounds are arranged in a 3D array
  (packing of ping-pong balls)
• usually only empirical formulas can be written
  for ionic compounds (because no real molecular
  unit in solid phase but extended lattice)
• usually solids but soluble in water insol. in
  organic sols.

73
Ionic Compounds

• total charge is neutral total () total (-)

• Cation Anion Charges Empirical Formula
• sodium (Na) chlorine (Cl) Na1 Cl-1 NaCl
• magnesium(Mg) nitrogen (N) Mg2 N-3
  Mg3N2
• aluminum (Al) bromine (Br) Al3 Br-1
  AlBr3
• barium (Ba) sulfate (SO4) Ba2 SO4-2
  BaSO4
• lithium (Li) carbonate (CO3) Li1 CO3-2
  Li2CO3
• nickel (Ni) chloride (Cl) Ni2 Cl-1
  NiCl2
• Ni3
  Cl-1 NiCl3

74
Ionic Compounds
Cell Face
Unit Cell
75
Ionic Compounds

• Sample exercise Which of the following
  compounds are molecular?
• CI4
• FeS
• P4O6
• PbF2

76
Ionic Compounds

• Sample exercise Which of the following
  compounds are molecular?
• CI4
• FeS
• P4O6
• PbF2

77
Ionic Compounds

• Sample exercise Write the empirical formulas
  for the compounds formed by the following ions
• a) Na and PO43-

78
Ionic Compounds

• Sample exercise Write the empirical formulas
  for the compounds formed by the following ions
• b) Zn2 and SO42-

79
Ionic Compounds

• Sample exercise Write the empirical formulas
  for the compounds formed by the following ions
• c) Fe3 and CO32-

80
Nomenclature naming inorganic compounds

• Method for unambiguously referring to the a. 15
  million known molecules)
• Organic compounds - containing C combined
  typically with H, O, N, and S (originally
  associated with living organisms but no longer
  relevant definition)
• Inorganic compounds - all other compounds

81
Nomenclature naming inorganic compounds

• Traditional names for compounds long known
  (ammonia NH3, water H2O, Zeises salt
  Pt(C2H4)Cl3-1, Muriatic Acid HCl, etc...)
• common names (somewhat systematic, ferrous
  chloride, cupric chloride, etc...)
• International Union of Pure and Applied Chemistry
  rules (IUPAC)

82
Nomenclature naming ionic compounds

• Ionic compounds are names based upon the
  component ions.
• Positive ion (cation) named and written first
• Negative ion (anion) named and written last
• Solve ambiguity in charge by using Roman numerals

• Cation Anion Compound Name
• Na Cl- NaCl sodium chloride
• Al3 O-2 Al2O3 aluminum oxide
• Fe2 O-2 FeO iron(II) oxide
• 
  (ferrous oxide)
• Fe3 O-2 Fe2O3 iron(III) oxide
• 
  (ferric oxide)

83
Nomenclature naming cations

• Monoatomic - take the name from the element
• Li1 lithium ion Sr3 strontium ion
• Ca2 calcium ion
• Polyatomic - only one common polyatomic cation
• NH41 ammonium ion
• Multiple Cationic Charge Possible - specify
  charge with Roman numerals to be unambiguous
• Fe2 iron(II) ion Fe3 iron(III) ion
• Cr6 chromium(VI) ion Cr5 chromium(V) ion
• For metals, older method used to distinguish
  between ions differing by one charge unit by
  adding suffix (-ous for lower charge, -ic for
  higher charge)
• Fe2 ferrous ion Fe3 ferric ion
• Co2 cobaltous ion Co3 cobaltic ion

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Nomenclature naming anions

• Monoatomic - add -ide suffix
• F-1 fluoride ion P-3 phosphide ion
• O-2 oxide ion B-5 boride ion
• Polyatomic - some common use -ide suffix
• OH-1 hydroxide ion CN-1 cyanide ion
• N3-1 azide ion O2-2 peroxide ion
• Oxyanions - (1) when only two, the one with less
  oxygen ends in -ite and the one with more oxygen
  ends with -ate
• NO2-1 nitrite ion NO3-1 nitrate ion
• SO3-2 sulfite ion SO4-2 sulfate ion
• Oxyanions- for species with more than two members
  use prefixes (hypo- less oxygen and per- more
  oxygen) ClO-1 ClO2-1 ClO3-1 ClO4-1
  hypochlorite chlorite chlorate
  perchlorate

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Nomenclature acids

• Acid - compound which yields H when dissolved in
  water
• write hydrogen first HCl, H2SO4, H3PO4, etc...
• anions which end in -ide use hydro- as prefix and
  -ic as suffix

Anion Acid Cl- (chloride) HCl (hydrochloric
acid) F- (fluoride) HF (hydrofluoric acid)

• oxyacids - replace -ate suffix of anion with -ic,
  
• replace -ite suffix of anion with -ous (leave
  prefixes!)

Anion Acid ClO2- (chlorite) HClO2 (chlorous
acid) ClO3- (chlorate) HClO3 (chloric
acid) ClO4-1 (perchloric) HClO4 (perchloric acid)
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Nomenclature molecular compounds

• Similar to ionic compounds
• More positive element (left and down on periodic
  table) named first (first in formula also)
• Second element name ends with -ide
• Use numbering prefixes if necessary

Prefix Number Mono- 1 Di- 2 Tri- 3 Tetra- 4 Pe
nta- 5 Hexa- 6 Hepta- 7 Octa- 8 Nona- 9 Deca- 10
Formula Name (text prob. 2.45) N2O5 dinitrogen
pentoxide IF7 iodine heptafluoride XeO3 xeon
trioxide SiCl4 silicon tetrachloride H2Se dihydrog
en selenide P4O6 tetraphosphorus hexoxide
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Nomenclature examples
Formula Name ZnCl2 (NH4)2SO4 FeF3 HBr HBrO4 SF6
HCN

• zinc(II) chloride
• ammonium sulfate
• iron(III) fluoride
• hydrobromic acid
• perbromic acid
• sulfur hexafluoride
• hydrogen cyanide

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End Chapter 2

• Atomic Theory
• Experiments leading to the discovery of atomic
  structure
• The Periodic Table
• Molecules and Ions
• Nomenclature