is.
Understandthestructureofanatom.
Learnwhatatomicweightsare.
Introducetheperiodictableandsomebasic
informationitincludes
8/26/2011
Atoms,MoleculesandIons
Chapter2
(Studentsareresponsiblefor
readingunits2.12.2)
WhataretheGoals(Chapter2)?
Understandwhatanatom Learntherelationshipbetweenatoms,elements,
compoundsandmolecules.
Learnwhationsare,whationiccompoundsare
andhowtheyarenamed.
Introducewhatorganicchemistryandorganic
moleculesare.
1
8/26/2011
Wherearetheatoms
inthisrepresentation
ofacompound?
Inthisdrawing,what
dothedifferent
colorsmean?
Penicillin
http://www.udel.edu/chem/white/C647/Penicillin.gif
Isthisanionic
compoundoran
organicmolecule?
Chemical Composition of the World: Atoms 101
indivisible, uncuttable
Allmatteriscomposedofatomswhichcannotbe
furthersplitintosmallerportions
Atomsarecompletelysolid
Atomsarehomogeneous,
withnointernalstructure
Betweenatomsthereisemptyspace
Atomsdifferinsize
Democritus (c.460c.370 B.C.)
2
8/26/2011
Chemical Composition of the World: Atoms 200
Eachelementiscomposedofextremelysmall
particlescalledatoms.
Allatomsofagivenelementareidenticalto
oneanotherinmassandotherproperties,but
theatomsofoneelementaredifferentfrom
theatomsofotherelements.
Theatomsofoneelementcannotbechanged
intoatomsofadifferentelementbychemical
reactions;atomsareneithercreatedor
destroyedinchemicalreactions.
Compoundsareformedwhenatomsofmore
thanoneelementcombine;agivencompound
alwayshasthesamerelativenumberandkind
ofatoms.
John Dalton (17661844)
3
8/26/2011
Chemical Composition of the World: Atoms 300
Thomsons
plum pudding model
Electrons embedded in a
shell of positive charge
Rutherfords model
Electrons randomly
circulating around nucleus
made of protons
RutherfordsExperiment Howdoesitsupporthis
hypothesisforatomicstructureratherthanThomsons?
4
8/26/2011
TheModernAtom
Mostoftheatomisempty
space.
Atomicradius=~1010
Aufoil
m
Nuclearradius=~1015 m
Volumeratio:
VAtom:VNucleus =~1015
Atoms,MoleculesandIons
The Modern Atom
The atom is made up of three
fundamental particles:
}
The proton, p+
Nuclear
The neutron, n0
The electron, e
Nearly all of the mass of
the atom is contained in
the nucleus
Nucleus
5
8/26/2011
Atoms,MoleculesandIons
The Modern Atom
proton
Mass/kg
Charge*
neutron
electron
1.67x1027
1.675x1027
9.1x1031
+1
0
1
Location
Nucleus
Nucleus
Atom
Stability
Stable
Unstable
outside the
nucleus
Stable
* In units of 1.6 x 1019 C
Atoms,MoleculesandIons
The Modern Atom Structure
A Small Dense Nucleus
Nuclear Radius: ~ 1015 m (1 fm)
Density of the nucleus:
~ 100,000,000,000,000 gcm3
(Densityofwater=1gcm3)
The mass of the electron is ~ 1/2000 that of the
proton and neutron most of the mass of the
atom is in the nucleus
6
8/26/2011
Atoms,MoleculesandIons
The Four Forces of Nature
There are only four fundamental forces found in
Nature.
Two are macroscopic
gravity
electromagnetism
Two are microscopic
strong nuclear force
weak nuclear force
Atoms,MoleculesandIons
The Four Forces of Nature
Two are very weak and are not important for the
structure of the atom
gravity
weak nuclear force
Two bind the atom together
strong nuclear force
electromagnetism
7
8/26/2011
Atoms,MoleculesandIons
The Modern Atom Structure
Structure of the nucleus not well understood:
Particles all interact with each other
Internal constituents of the protons and
neutrons interact
Nuclear force, the strong nuclear force, not
well understood
Very high energies needed for study!
Atoms,MoleculesandIons
The Modern Atom Structure
Structure of the atom (outside the nucleus) is well
understood:
Electrons exist in a cloud around the nucleus
Bound to the central positive nucleus by the
electromagnetic force:
Opposite Charges Attract
Experimentally easy energies needed for study
8
8/26/2011
Atoms,MoleculesandIons
The Chemical Atom
Atoms are neutral they have no electrical charge
(total charge = 0)
There are equal numbers of protons in the
nucleus and electrons in the atom.
The charges on the electron and the proton are
equal.
Shorthand for an Atom
(Basic information in a periodic table)
17
Atomic Number
Cl
Atomic Symbol
35.453
Average Atomic Mass (amu)
Molar Mass (g)
9
8/26/2011
AtomicSymbols
Chemical elements are abbreviated with a
symbol, usually but not always abbreviated to
their name in English:
Calcium
Barium
Chlorine
Ca
Ba
Cl
Radon
Magnesium
Oxygen
Rn
Mg
O
Elements, whose symbols are not always
abbreviated to their name:
Sodium
Potassium
Silver
Gold
Mercury
Tungsten
Na
K
Ag
Au
Hg
W
(Latin Natria)
(Latin Kalia)
(Latin Argentum)
(Latin Aurum)
(Latin Hydrargyrum)
(from the mineral Wolframite)
10
8/26/2011
AtomicNumbers
The atomic number is the number of protons in
an atom.
The atomic number must be the number of
electrons in the atom as atoms have equal
numbers of protons and electrons.
AverageAtomicMass
The listed atomic mass is the average mass for
this atom.
This value is expressed in atomic mass units
for convenience (1 amu = 1.66054 1024 g).
The expression of this as an average value
hints that an atoms of one element may have
different masses?
This value is also the molar mass (grams). We
will discuss this concept later.
11
8/26/2011
Isotopes
The number of protons determines the chemical
identity of the element .
The number of neutrons in the nucleus does not
affect the number of electrons and therefore the
chemical identity (or the atomic number).
Atoms which have different numbers of neutrons
and the same number of protons are called
Isotopes
ShorthandtoindicateaspecificIsotope
ofanAtom: Beryllium9
mass number
atomic number (Z)
9
atomic
Be symbol
4
Mass number - atomic number = Neutrons
4 protons & 5 neutrons Note:providingboththe
elementalsymboland
4 electrons
charge = (+4) + (-4) = 0 theatomicnumber,Z,is
oftenconsidered
redundant.Zisoften
skipped,forexample,9Be
12
8/26/2011
Example:Howmanyprotons,neutronsandelectronsaretherein
thefollowingtypesofatoms(isotopes)?
n0
ep+
1. Hydrogen 11H
1
0
1
2. Hydrogen 22H
1
1
1
1
2
1
6
7
6
(deuterium)
3. Hydrogen 33H
(tritium)
4. Carbon 1313C
5.
16O
8
8
8
6.
81Br
35
46
35
7.
131Xe
54
77
54
AtomicMasses(more)
Atomicmassesforanatom(1isotope)arenotall
exactintegervalues!
Themassofone31Patomis30.99376amu.
Wehavedefinedthemassof12Casexactly 12
atomicmassunits(amu)andthenmeasureda
relativeweightforotheratoms(isotopes)
1amu =(1/12)massof12Cbydefinition
butthemassof13Cis13.003355amu
13
8/26/2011
Examples
Isotope
Mass (amu)
1H
1.0078
4He
4.00260
8Be
8.005305
12C
12.000000
16O
15.994915
24Mg
23.985042
AverageAtomicMass
The atomic mass listed in the periodic table is
the average mass for this element. An element
like, Cl, has more than one isotope in nature,
and the average (35.453) takes this into
account!
17
Note:theAverageAtomicMass
isalsocalledtheAtomicWeight
Cl
35.453
14
8/26/2011
Atoms,MoleculesandIons
To calculate the average atomic mass of the
element, multiply the abundance of the isotope by
the mass of the isotope and add:
58Ni
60Ni
61Ni
62Ni
64Ni
68.077%
26.223%
1.1399%
3.635%
0.9256%
57.9353 x 68.077/100 = 39.4406
59.9308 x 26.223/100 = 15.7157
60.9311 x 1.1399/100 = 0.6946
61.9283 x 3.635/100 = 2.2511
63.9280 x 0.9256/100 = 0.5917
58.6937
15
8/26/2011
ExampleforC
The
12C
isotope = 12.000000 amu's
Pure carbon:
98.892 % of all carbon atoms on earth are 12C atoms
1.108 % of all carbon atoms on earth are 13C atoms.
So the average mass of carbon a carbon atom is
(0.98892)(12.0000 amu
12C
) + (.01108)(13.0033 amu
13C
)
= 12.011 amu
16
8/26/2011
Atoms,MoleculesandIons
The Periodic Table
ThePeriodicTableisanorderedarrayofthe
elements,withrisingatomicnumber.
First written down by Dimitri
Mendelev as a list of the
elements with increasing atomic
Mass. The elements naturally
grouped themselves by chemical
properties.
DimitriMendelev
(1834 1907)
The Periodic Table
Containsinformationwhich,ifyouknowtherules,iseasyto
accessanduse.
ThehorizontalrowsarecalledPERIODS the2nd period:
3Li,4Be,5B,6C,7N,8O,9F,10Ne
Elementslyingwithinaperiodareexpectedtohavedifferent
chemicalproperties
Elementswithsimilarchemicalandphysicalpropertiesliein
verticalcolumnscalledGROUPS forexample,Group1A(1):
Li,Na,K,Rb,Cs,Fr
Elementsingroupshaveelectronconfigurationsfollowingvery
similarpatterns(Ch.6)
17
8/26/2011
Atoms,MoleculesandIons
The Radioactive elements
s block
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Fr
86
Ca
20
Sr
38
Ba
56
Ra
88
p block
H
1
3
4
5
6
7
He
2
d block
Sc
21
Y
39
Lu
71
Lr
103
Ti
22
Zr
40
Hf
72
Rf
104
V
23
Nb
41
Ta
73
Db
105
Cr
24
Mo
42
W
74
Sg
106
Mn
25
Tc
43
Re
75
Bh
107
Fe
26
Ru
44
Os
76
Hs
108
Co
27
Rh
45
Ir
77
Mt
109
Ni
28
Pd
46
Pt
78
Ds
110
Cu
29
Ag
47
Au
79
Rg
111
Zn
30
Cd
48
Hg
80
112
B
5
Al
13
Ga
31
In
49
Tl
81
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
f block
La
57
Ac
89
Ce
58
Th
90
Pr
59
Pa
91
Nd
60
U
92
Pm
61
Np
93
Sm
62
Pu
94
Eu
63
Am
95
Gd
64
Cm
96
Tb
65
Bk
97
Dy
66
Cf
98
Ho
67
Es
99
Er
68
Fm
100
Tm
69
Md
101
Yb
70
No
102
Atoms,MoleculesandIons
Gases at room temperature
s block
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Fr
86
Ca
20
Sr
38
Ba
56
Ra
88
p block
H
1
3
4
5
6
7
He
2
d block
Sc
21
Y
39
Lu
71
Lr
103
Ti
22
Zr
40
Hf
72
Rf
104
V
23
Nb
41
Ta
73
Db
105
Cr
24
Mo
42
W
74
Sg
106
Mn
25
Tc
43
Re
75
Bh
107
Fe
26
Ru
44
Os
76
Hs
108
Co
27
Rh
45
Ir
77
Mt
109
Ni
28
Pd
46
Pt
78
110
Cu
29
Ag
47
Au
79
111
Zn
30
Cd
48
Hg
80
112
B
5
Al
13
Ga
31
In
49
Tl
81
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
f block
La
57
Ac
89
Ce
58
Th
90
Pr
59
Pa
91
Nd
60
U
92
Pm
61
Np
93
Sm
62
Pu
94
Eu
63
Am
95
Gd
64
Cm
96
Tb
65
Bk
97
Dy
66
Cf
98
Ho
67
Es
99
Er
68
Fm
100
Tm
69
Md
101
Yb
70
No
102
18
8/26/2011
Atoms,MoleculesandIons
Gases and liquids at room
temperature
s block
1
H
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Fr
86
Ca
20
Sr
38
Ba
56
Ra
88
3
4
5
6
7
p block
He
2
d block
Sc
21
Y
39
Lu
71
Lr
103
Ti
22
Zr
40
Hf
72
Rf
104
V
23
Nb
41
Ta
73
Db
105
Cr
24
Mo
42
W
74
Sg
106
Mn
25
Tc
43
Re
75
Bh
107
Fe
26
Ru
44
Os
76
Hs
108
Co
27
Rh
45
Ir
77
Mt
109
Ni
28
Pd
46
Pt
78
110
Cu
29
Ag
47
Au
79
111
Zn
30
Cd
48
Hg
80
112
B
5
Al
13
Ga
31
In
49
Tl
81
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
f block
La
57
Ac
89
Ce
58
Th
90
Pr
59
Pa
91
Nd
60
U
92
Pm
61
Np
93
Sm
62
Pu
94
Eu
63
Am
95
Gd
64
Cm
96
Tb
65
Bk
97
Dy
66
Cf
98
Ho
67
Es
99
Er
68
Fm
100
Tm
69
Md
101
Yb
70
No
102
Themoretotheleftandtothebottomoftheperiodictable,the
moreMETALLIC thecharacterofanelement
Csis more (less,more)metallicthanK
Alis less (less,more)metallicthanRb
Themoretotherightandtothetopoftheperiodictable,themore
NONMETALLIC thecharacterofanelement
Fis more (less,more)nonmetallicthanC
Ois more (less,more)nonmetallicthanSi
Elementswithsomemetallicandsomenonmetallicpropertiesare
calledsemimetalsor METALLOIDS:B,Si,Ge,As,Sb,Te
19
8/26/2011
Atoms,MoleculesandIons
The Nonmetals
s block
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Fr
86
Ca
20
Sr
38
Ba
56
Ra
88
p block
H
1
3
4
5
6
7
He
2
d block
Sc
21
Y
39
Lu
71
Lr
103
Ti
22
Zr
40
Hf
72
Rf
104
V
23
Nb
41
Ta
73
Db
105
Cr
24
Mo
42
W
74
Sg
106
Mn
25
Tc
43
Re
75
Bh
107
Fe
26
Ru
44
Os
76
Hs
108
Co
27
Rh
45
Ir
77
Mt
109
Ni
28
Pd
46
Pt
78
110
Cu
29
Ag
47
Au
79
111
Zn
30
Cd
48
Hg
80
112
B
5
Al
13
Ga
31
In
49
Tl
81
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
f block
La
57
Ac
89
Ce
58
Th
90
Pr
59
Pa
91
Nd
60
U
92
Pm
61
Np
93
Sm
62
Pu
94
Eu
63
Am
95
Gd
64
Cm
96
Tb
65
Bk
97
Dy
66
Cf
98
Ho
67
Es
99
Er
68
Fm
100
Tm
69
Md
101
Yb
70
No
102
GeneralCharacteristicsofNonmetals
Bad conductors of electricity
often insulators or semiconductors
conductivity rises with increasing
temperature
Bad conductors of heat
Brittle, not maleable, not ductile
20
8/26/2011
Atoms,MoleculesandIons
The Nonmetals and
The Metals
s block
1
H
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Fr
86
Ca
20
Sr
38
Ba
56
Ra
88
3
4
5
6
7
p block
He
2
d block
Sc
21
Y
39
Lu
71
Lr
103
Ti
22
Zr
40
Hf
72
Rf
104
V
23
Nb
41
Ta
73
Db
105
Cr
24
Mo
42
W
74
Sg
106
Mn
25
Tc
43
Re
75
Bh
107
Fe
26
Ru
44
Os
76
Hs
108
Co
27
Rh
45
Ir
77
Mt
109
Ni
28
Pd
46
Pt
78
110
Cu
29
Ag
47
Au
79
111
Zn
30
Cd
48
Hg
80
112
B
5
Al
13
Ga
31
In
49
Tl
81
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
f block
La
57
Ac
89
Ce
58
Th
90
Pr
59
Pa
91
Nd
60
U
92
Pm
61
Np
93
Sm
62
Pu
94
Eu
63
Am
95
Gd
64
Cm
96
Tb
65
Bk
97
Dy
66
Cf
98
Ho
67
Es
99
Er
68
Fm
100
Tm
69
Md
101
Yb
70
No
102
GeneralCharacteristicsofMetals
Good or excellent conductors of electricity
conductivity falls with increasing
temperature
are often superconductors at low
temperature
Good conductors of heat
Often maleable and ductile
21
8/26/2011
Atoms,MoleculesandIons
Dalton and Compound Atoms
John Dalton rejuvenated the
atomic theory and used the
terms compound atoms and
atoms to define the basic
building blocks of matter.
Daltons compound atoms are
todays
MOLECULES
Atoms,MoleculesandIons
Compounds and Molecules
The chemistry of each element is determined by
the number and energy of the outer valence
electrons.
The Atomic Number, Z, shows number of protons in the
nucleus.
The atom is neutral and so the number of protons equals
the number of electrons.
22
8/26/2011
Wherearetheatoms
inthisrepresentation
ofacompound?
Inthisdrawing,what
dothedifferent
colorsmean?
Penicillin
http://www.udel.edu/chem/white/C647/Penicillin.gif
Isthisanionic
compoundoran
organicmolecule?
Atoms,MoleculesandIons
Chemistry the and Modern Atom
Atomsbindtogetherusingtheirelectrons.
Chemistryisbasedinthephysicsofelectronsin
atoms.
Weunderstandelectronsinatomswellenoughto
understandchemistryatahighlevel.
23
8/26/2011
Molecules
A molecule is a structure
where two or more atoms
are bound together by
sharing the outer electrons
in a covalent bond.
B
5
C
6
N
7
O
8
F
9
Si
14
P
15
S
16
Cl
17
Ge
32
As
33
Se
34
Br
35
Sb
51
Te
52
I
53
Xe
54
Most molecular species are
formed by the nonmetals
Atoms,MoleculesandIons
A molecule has a definite chemical composition
and we write a molecular formula for the
composition:
Elemental sulfur has the molecular formula
S8
Number of atoms
in the molecule
Chemical Symbol
24
8/26/2011
Atoms,MoleculesandIons
Some elements whose
natural forms occur as
molecules include
Nitrogen
Phosphorous
B
5
N
7
O
8
F
9
Si
14
P
15
S
16
Cl
17
Ge
32
As
33
Se
34
Br
35
Sb
51
N2
P4
C
6
Te
52
I
53
C
6
N
7
O
8
F
9
Si
14
P
15
S
16
Cl
17
Ge
32
As
33
Se
34
Br
35
Sb
51
Te
52
I
53
Xe
54
Atoms,MoleculesandIons
Some elements whose
natural forms occur as
molecules include
Nitrogen
Phosphorous
Arsenic
N2
P4
As4
Oxygen
Sulfur
B
5
O2
S8
Xe
54
25
8/26/2011
Atoms,MoleculesandIons
Some elements whose
natural forms occur as
molecules include
Nitrogen
Phosphorous
Arsenic
N2
P4
As4
Oxygen
Sulfur
O2
S8
B
5
C
6
N
7
O
8
F
9
Si
14
P
15
S
16
Cl
17
Ge
32
As
33
Se
34
Br
35
Sb
51
Te
52
I
53
Fluorine
Chlorine
Bromine
Iodine
Xe
54
F2
Cl2
Br2
I2
Moleculescontainingmorethanone
elementarecompounds.
Methane
CH4
1 Carbon
4 Hydrogens
Ethanol
C2H6O
2 Carbons
6 Hydrogens
1 Oxygen
Sulfuric Acid
H2SO4
2 Hydrogens
1 Sulfur
4 Oxygens
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Atoms,MoleculesandIons
But the three dimensional structure of the
molecule is best represented using models or
chemical drawing software (e.g. ChemDraw) as
the reactivity and chemistry of a molecule takes
place in three dimensions
MoleculesandMolecularCompounds
InaMOLECULAR FORMULA atomsofdifferentelementsare
typically bunchedupandcounted.H2SO4
H
O
STRUCTURAL FORMULA O = S = O
showschemicalbonds
betweenatomsinamolecule
O
H
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CONDENSED FORMULA certainatomsaregroupedtogether
toemphasizeanimportantpartofamolecule
Ethanol
Molecularformula: C2H6O
Condensedformula: CH3CH2OH
Structuralformula:
Hydroxyl analcohol
functional group
MolecularandEmpiricalFormulas
Empirical Formula Provides the relative numbers of atoms
contained in the molecule.
CH
Molecular Formula Provides the actual number of each type
of atom in the molecule.
C6H6
Structural Formula Describes the connectivity of the
molecule. For benzene the structural formula is:
H
H
H
C
C
C
C
C
C
H
H
H
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Atoms,MoleculesandIons
Empirical formula
Molecular
Acetic Acid: CH2O
Structural
C2H4O2
H
H
C
O
C
O
H
H
H
Glucose
CH2O
C6H12O6
H
H
H
OH H
H
C
C
C
C
C
OH OH OH H
Formaldehyde CH2O
CH2O
C
O
OH
O
C
H
H
MoleculeRepresentation
Lines representbonds
Givessomeindicationof
the3Dstructureandbond
angles
Shows3Dstructureand
bondangles can show
relativeatomsize
Showsthesizesofatoms,
butbondsandgeometry
arehardertosee
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WritingaNameforaMolecularFormula
The first element in the name is the one
farthest to the left (in the periodic table)
and
lowest in the group (in the periodic table)
Hydrogen and oxygen are sometimes exceptions
WritingaNameforaMolecularFormula
Prefixes denote the number of atoms
Mono
1
Hexa
Di
2
Hepta
Tri
3
Octa
Tetra
4
Nona
Penta
5
Deca
6
7
8
9
10
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WritingaNameforaMolecularFormula
The second name drops the suffix and adds
ide
instead
chlorine chloride
oxygen
oxide
WritingaNameforaMolecularFormula
Example
1 phosphorous atoms
5 fluorine atoms
Phosphorous Pentafluoride
PF5
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WritingaNameforaMolecularFormula
Example
S2F10
2 sulfur atoms
disulfur
10 fluorine atoms
decafluoride
disulfur decafluoride
MolecularCompounds
MoreExamples
CO=carbonmonoxide
ClO2 =chlorinedioxide
Someexceptions H2O,whichaccordingtothe
rulesshouldbecalleddihydrogen monoxide
isalwayscalledwater
NH3,ornitrogentrihydride, isalwayscalled
ammonia.
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OrganicCompounds
Moleculesthatincludecarbon(especiallyCC
bonds)arereferredtoasorganiccompounds
ororganicmolecules.
TypicallyorganiccompoundsalsoincludeH,O,
andN(otherelementscanbeincludedtoo)
Moleculesthatarenotorganiccompounds
arecalledinorganiccompounds.Inorganic
compoundsusuallydontcontainCorCC
bonds.
SimpleOrganicCompounds
Formula
Structure
Name / Uses
CH4
Methane - gas used for cooking
C 2H 6
Ethane
C 3H 8
Propane - heating fuel
C4H10
Butane - lighter / camping fuel
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Alcohols
General
Formula
CnH2n+1OH
Series Name
Alcohols
Details
Examples
Alcohols have the
OH (hydroxyl)
group in the
molecule.
CH3OH
A group of atoms
that gives an
organic series its
distinctive
character is called
a functional
group.
Structures
Methanol
wood alcohol
C2H5OH
Ethanol
alcohol
PhysicalPropertiesofMolecules
Substances that are made up of molecules tend
to be
mechanically soft
low melting and boiling
electrical insulators in solution and in the
solid state
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Atoms,MoleculesandIons
Atoms are neutral
equal numbers of protons (in the nucleus)
and electrons (outside the nucleus)
charge on the electron and proton is equal
An atom that gains or loses one or more
electrons is called an
ION
Atoms,MoleculesandIons
An atom that loses one or more electrons is
positively charged and is called a
CATION
An atom that gains one or more electrons is
negatively charged and is called an
ANION
PROTONS ARE NOT TRANSFERRED FROM THE
NUCLEUS!!!
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Note:ioniccompounds DONOT appearasindividualmolecules,
but:
ifinsolutionormolten,theyappearasindividualions
ifinsolid,theyappearas3Dcrystallatticesduetoregularly
spacedionsofalternatingcharges(+and)
theybreakalongthecrystalplanes
Strongcrystallatticesoften mean:
Hardcrystals
Highmeltingpoints
Lowsolubilityinwater
(moreinCh.8)
Example:Howmanyprotons,neutronsandelectronsaretherein
thefollowingions?
p+
n0
e1.
24Mg2+
12
12
10
2.
25Mg2+
12
13
10
3.
26Mg2+
12
14
10
4.
16O2
8
8
10
5.
56? 3+
56Fe
26
30
23
Isoelectronic ions,ie.havethe
same#ofelectrons
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Atoms,MoleculesandIons
Ionic compounds are held together by
electrostatic forces between the ions they are
crystalline and there is no minimum unit
analogous to a molecule
Which element which ion?
This depends on the electronic structure of
the atom
Mono,di andtrications
1
H
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Ca
20
Sr
38
Ba
56
3
4
5
6
He
2
Trications:Al3+,Ga3+
d block
Sc
21
Y
39
Lu
71
Ti
22
Zr
40
Hf
72
V
23
Nb
41
Ta
73
Cr
24
Mo
42
W
74
Mn
25
Tc
43
Re
75
Fe
26
Ru
44
Os
76
Co
27
Rh
45
Ir
77
Ni
28
Pd
46
Pt
78
Cu
29
Ag
47
Au
79
Zn
30
Cd
48
Hg
80
B
5
Al
13
Ga
31
In
49
Tl
81
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
Dications:Be2+,Mg2+,Ca2+,Sr2+,Ba2+
Sn2+,Pb2+
Monocations:Li+,Na+,K+,Rb+,Cs+
TrianionsN3,P3
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
Monoanions
Dianions
O2,S2
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Atoms,MoleculesandIons
Transition metals can from ions with more than
one charge. Common ones include
Ti
Ti3+ Ti4+
Co Co2+ Co3+
V
V3+ V4+ V5+
Ni Ni2+
Mn Mn2+ Mn4+ Mn5+
Cu Cu+ Cu2+
Fe Fe2+ Fe3+
Atomsofelementsontheleftside
oftheperiodictabletendto:
a)
b)
c)
d)
gainelectrons.
loseelectrons.
keepelectrons.
shareelectrons.
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1
H
1
2
Li
3
Na
11
Be
4
Mg
12
K
19
Rb
37
Cs
55
Ca
20
Sr
38
Ba
56
3
4
5
6
He
2
B
5
Al
13
Ga
31
In
49
Tl
81
d block
Sc
21
Y
39
Lu
71
Ti
22
Zr
40
Hf
72
V
23
Nb
41
Ta
73
Cr
24
Mo
42
W
74
Mn
25
Tc
43
Re
75
Fe
26
Ru
44
Os
76
Co
27
Rh
45
Ir
77
Ni
28
Pd
46
Pt
78
Cu
29
Ag
47
Au
79
Zn
30
Cd
48
Hg
80
C
6
Si
14
Ge
32
Sn
50
Pb
82
N
7
P
15
As
33
Sb
51
Bi
83
O
8
S
16
Se
34
Te
52
Po
84
F
9
Cl
17
Br
35
I
53
At
85
Ne
10
Ar
18
Kr
36
Xe
54
Rn
86
These cations and anions are formed from atoms
but we can form anions and cations from
molecules. These are termed
POLYATOMICIONS
PolyatomicIons
These species exists as anions and cations and
contain several atoms bound together in the same
way as a molecule covalently but with one or
more positive or negative charge.
H
2
O
O
S
O
O
N
O
N
O
O
H
S
H
H
O
O
C
P
O
O
O
H
H
H
3
2
O
H
O
O
H
H
H
C
C
C
C
C
H
C
S
H
H3C
CH3
CH3
H
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8/26/2011
Othernotableanions(seeTable2.5):
OH
hydroxide ion
2
O
oxideion
nitrideion
N
HCO3
HSO4
HSO3
HPO42
H2PO4
hydrogencarbonate ion(bicarbonate)
hydrogensulfate ion(bisulfate)
hydrogensulfite ion(bisulfite)
hydrogenphosphate ion
dihydrogen phosphate ion
Knowingchargesofionsallowsyoutowritecorrectformulaunits of
ioniccompounds whichreflectratios ofcationstoanions
Example:CaCl2 isaformulaunitinwhichthereis:
1 Ca2+cation
per2 Cl anions.
Ca5(PO4)3(OH)isaformulaunitinwhichthereare:
5 Ca2+cations
per3 PO43 anions and1 OH anion
Acids,basesandsalts
Svante Arrhenius defined
an acid is a compound which dissolves
in water or reacts with water to give
hydronium ions, H3O+(aq)
a base is a compound which dissolves
in water or reacts with water to give
hydroxide ions, OH (aq)
SvanteArrhenius
(1859 1927)
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8/26/2011
Binary(madeof2elements):
Anions:
prefix: hydro ,suffix:ic
suffix:ide
HCl(aq)
hydrochloric acid
Cl
chloride
HBr(aq)
hydrobromic acid
Br
bromide
iodide
HI(aq)
hydriodic acid
I
HF(aq)
hydrofluoric acid
F
fluoride
H2S(aq)
hydrosulfuric acid
S
sulfide
HCN(aq)
hydrocyanic acid
CN cyanide
Notes: ClassicacidformulasstartwithH!
Acidsarenot ionicmolecules,buttheydodissociateinto
protons(H+)andanions.
Acidmolecules areneutral,however,notallsubstances
whichactasacidsmustbeneutral(Chem 1202).
Chargesofanions resultfromthenumberofacidic
hydrogenatomsinanacid(forexample,S2 inH2S).
What about polyatomic ions?
Oxyacids (containoxygen): Anions:
suffix-ous or-ic
suffix-ite or-ate
HNO2
HNO3
H2SO3
H2SO4
H3PO3
H3PO4
nitrous acid
nitric acid
sulfurous acid
sulfuric acid
phosphorous acid
phosphoric acid
NO2
NO3
SO32
SO42
PO33
PO43
HClO
HClO2
HClO3
HClO4
hypochlorous acid
chlorous acid
chloric acid
perchloric acid
hypochlorite
ClO
ClO2
chlorite
ClO3
chlorate
perchlorate
ClO4
nitrite
nitrate
sulfite
sulfate
phosphite
phosphate
Learntorecognizetheseformulas
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8/26/2011
HBrO3
HIO3
bromic acid
iodic acid
BrO3 bromate
IO3
iodate
HMnO4 permanganic acid
H2CrO4
chromic acid
H2Cr2O7 dichromic acid
MnO4 permanganate
CrO42 chromate
Cr2O72 dichromate
carbonic acid
H2CO3
H2C2O4
oxalic acid
CH3COOHacetic acid
(ethanoic acid)
CO32
carbonate
C2O42 oxalate
CH3COO acetate
(ethanoate)
Learntorecognizetheseformulas
IonicCompounds
Letsreviewsomeofthefeaturesofionic
compounds
Metalsgiveupelectronstoformpositively
chargedcations.
Nonmetalsgainelectronstoformnegatively
chargedanions.
Ioniccompoundsareformedfromthe
Coulombic interactionbetweencationsand
anions.
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IonicCompound
Cations+Anions=> SALT
FormulaNaClreflectsChargeBalance
compoundmustbeneutral
EmpiricalFormula SmallestWholeNumber
Ratio
(Na1+)x(S2-)y = Na2S1
(V4+)x(O2-)y = V2O4 = VO2
Remove common factor
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8/26/2011
Ions
Na+ +Cl
Zn2+ +S2
Ca2+ +F
Al3+ +O2
K+ +SO42
NH4+ +S2
NaCl
ZnS
CaF2
Al2O3
K2SO4
(NH4)2S
IonicCompounds
Whenwenameanioniccompound,wewrite
(1)cationcomesfirstfollowedbythenameofthe
anion,changingthenameoftheaniontoend
inide formonotomicanions.
Examples
NaCl sodiumchloride
ZnI2 zinciodide
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8/26/2011
Formulas and Naming (Nomenclature) of Ionic Compounds (2.8)
+1
1) potassiumcationK
andBr1 bromideanion
KBr
1
1
KBr
potassiumbromide
Note:IttakesoneK+cationpereachBr anion
K+ +Br KBr
+1
2) potassiumcationK
andSO42 sulfateanion
K 2 (SO4) 1
K2SO4
potassiumsulfate
+cationspereachSO anion
Note:IttakestwoK
4
2K+ +SO4 K2SO4
3)
Ca2+ plusCO32
Ca2(CO3)2
CaCO3
4)Ca2+ plusPO43
Ca3(PO4)2
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MoreExamples
NaNO3
Ag2CO3
(NH4)2SO4
sodiumnitrate
silvercarbonate
ammoniumsulfate
IonicCompounds
Fortransitionmetals:
cationsofdifferingchargesthepositive
chargeisgivenbyaromannumeralin
parentheses
CuO copper(II)oxide(Cupric)
Cu2O copper(I)oxide(Cuprous)
Cr2O3 chromium(III)oxide
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8/26/2011
Oxyanions
polyatomicanionscontainingoxygen
CO32
NO3
ClO3
PO43
SO42
Carbonate ion
Nitrate ion
Chlorate ion
Phosphate ion
Sulfate ion
Note that -ate ending!
Oxyanions
Theendingite isusedfortheoxyanionwiththe
samecharge,butonelessoxygen thantheate
oxyanion.
NO2
SO32
PO33
ClO2
Nitriteion(asopposetoNO3)
Sulfiteion
Phosphite ion
Chloriteion
47
8/26/2011
Oxyanions
Theprefixper isusedifthereisanoxyanion with
thesamechargebutonemoreoxygenthanthe
ate oxyanion,
whiletheprefixhypo isusedifthereisan
oxyanion withthesamechargebutoneless
oxygenthantheite oxyanion.
ClO4
ClO3
ClO2
ClO
Formula
percholorate ion
chlorateion
chloriteion
hypochloriteion
Name
IdentifiedTypesofIons
NH4+ &S2
(NH4)2S
ammoniumsulfide
Ca(ClO)2
calciumhypochlorite
Ca2+ & ClO
Co2O3
cobalt(III)oxide
Co3+ & O2
CoO
cobalt(II)oxide
Co2+ & O2
NaHCO3
Mg3(PO4)2
sodiumhydrogencarbonate
magnesiumphosphate
Na+ &
HCO3
Mg2+ & PO43
LiClO4
lithiumperchlorate
Li+ &
ClO4
AlPO4
aluminumphosphate
Al3+ &
PO43
Ca(OH)2
calciumhydroxide
SnCl2
tin(II)chloride
CuSO4
copper(II)sulfate
(NH4)2Cr2O7
Ca2+ & OH
Sn2+ &Cl
Cu2+ & SO42
ammoniumdichromateNH4+ &Cr2O72
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Protons, Electrons, Neutrons
Matter
Atoms
Molecules
Structure
Molecular,
of Matter
Elements,
Compounds,
Molecules,
Ions, Acids, Salts,
Naming Rules
Chemical
& Physical
Properties
New Molecules
Ions
Atoms
All Science and Engineering Involves Matter
49