Chemistry 120 Chemical Composition of the World: Atoms 101 “indivisible, uncuttable” All matter...
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Transcript of Chemistry 120 Chemical Composition of the World: Atoms 101 “indivisible, uncuttable” All matter...
Chemistry 120
Chemical Composition of the World: Atoms 101
“indivisible, uncuttable”All matter is composed of atoms which cannot be further split into smaller portionsAtoms are completely solidAtoms are homogeneous, with no internal structureBetween atoms there is empty spaceAtoms differ in size
Democritus (c.460-c.370 B.C.)
Atoms, Molecules and Ions
Chemistry 120
John Dalton (1766-1844)
Chemical Composition of the World: Atoms 200
Atoms, Molecules and Ions
Chemistry 120
Chemical Composition of the World: Atoms 300
Thomson’s“blueberry muffin” modelElectrons embedded in a shell of positive charge
Rutherford’s modelElectrons randomly circulating around nucleus made of protons
Atoms, Molecules and Ions
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom
Most of the atom is empty space.
Atomic radius = ~ 10-10 m
Nuclear radius = ~ 10-15 m
Volume ratio:
VAtom: VNucleus = ~ 1015
Au foil
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom
The atom is made up of three fundamental particles
The proton, p+
The neutron, n0
The electron, e-
Most of the mass of the atom is contained in the nucleus
Nucleus
}Nuclear
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom
proton neutron electron
Mass/kg 1.67x10-27 1.675x10-27 9.1x10-31
Charge* +1 0 -1
Location Nucleus Nucleus Atom
Stability Stable Unstable Stableoutside the nucleus
* In units of 1.6 x 10-19 C
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom - Structure
A Small Dense Nucleus
Nuclear Radius: ~ 10-15 m (1 fm)
Density of the nucleus:
~ 100,000,000,000,000 gcm-3
Density of water = 1 gcm-3
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
Chemistry 120
Atoms, Molecules and Ions
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
Chemistry 120
Atoms, Molecules and Ions
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
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom - Structure
Structure of the nucleus not well understood:
Particles all interact with each other
Chemistry 120
Atoms, Molecules and Ions
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
Chemistry 120
Atoms, Molecules and Ions
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
Chemistry 120
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, Molecules and Ions
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom - Structure
Structure of the atom is well understood:
Electrons flow around the nucleus
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom - Structure
Structure of the atom is well understood:
Electrons flow around the nucleus
Bound to the central positive nucleus by the electromagnetic force:
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom - Structure
Structure of the atom is well understood:
Electrons flow around the nucleus
Bound to the central positive nucleus by the electromagnetic force:
Opposite Charges Attract
Chemistry 120
Atoms, Molecules and Ions
The Modern Atom - Structure
Structure of the atom is well understood:
Electrons flow around the nucleus
Bound to the central positive nucleus by the electromagnetic force:
Opposite Charges Attract
Experimentally easy energies needed for study
Chemistry 120
Chemistry and the Modern Atom
Atoms bind together using their electrons
Chemistry is based in the physics of electrons in atoms
We understand electrons in atoms well enough to understand chemistry at a high level
Atoms, Molecules and Ions
Chemistry 120
The Chemical Atom
Atoms are neutral – they have no electrical charge
There are equal numbers of protons in the nucleus and electrons in the atom.
The charges on the electron and the proton are equal.
Atoms, Molecules and Ions
Chemistry 120
The Chemical Atom
Atomic numbers and mass numbers
The chemistry of each element is determined by the number and energy of the outer valence electrons.
The atom is neutral and so the number of protons equals the number of electrons.
The Atomic Number, Z, shows number of protons in the nucleus.
Atoms, Molecules and Ions
Chemistry 120
The Chemical Atom
The order of the elements in the periodic table is in the order of increasing number of protons in the nucleus and therefore electrons in the atom.
The mass number is the atomic mass and we write an element as
where X is the chemical symbol, A is the mass number and Z is the atomic number.
Atoms, Molecules and Ions
AZ X
42He
Chemistry 120
For Helium, He,
Mass = 4
Atomic number = 2
Atoms, Molecules and Ions
42He}
Chemistry 120
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.
Atoms which have different numbers of neutrons and the same number of protons are called
Isotopes
Atoms, Molecules and Ions
Chemistry 120
The mass of an atom A is given by
A = Z + N
Number of protons Number of neutrons
Isotopes have different masses but are chemically identical
58Ni 68.27 16O 99.762 60Ni 26.1 17O 0.03861Ni 1.13 18O 0.2 62Ni 3.59 64Ni 0.91
Atoms, Molecules and Ions
Chemistry 120
To calculate the natural mass of the element, multiply the abundance of the isotope by the mass of the isotope and add:
58Ni 68.27 60Ni 26.161Ni 1.1362Ni 3.59 64Ni 0.91
Atoms, Molecules and Ions
Chemistry 120
To calculate the natural mass of the element, multiply the abundance of the isotope by the mass of the isotope and add:
58Ni 68.27% 58 x 68.27/100 =60Ni 26.1% 60 x 26.1/100 =61Ni 1.13% 61 x 1.13/100 = 62Ni 3.59% 62 x 3.59/100 =64Ni 0.91% 64 x 0.91/100 =
Atoms, Molecules and Ions
Chemistry 120
To calculate the natural mass of the element, multiply the abundance of the isotope by the mass of the isotope and add:
58Ni 68.27% 58 x 68.27/100 = 39.596660Ni 26.1% 60 x 26.1/100 = 15.6661Ni 1.13% 61 x 1.13/100 = 0.689362Ni 3.59% 62 x 3.59/100 = 2.225864Ni 0.91% 64 x 0.91/100 = 0.5824
Atoms, Molecules and Ions
Chemistry 120
To calculate the natural mass of the element, multiply the abundance of the isotope by the mass of the isotope and add:
58Ni 68.27% 58 x 68.27/100 = 39.596660Ni 26.1% 60 x 26.1/100 = 15.6661Ni 1.13% 61 x 1.13/100 = 0.689362Ni 3.59% 62 x 3.59/100 = 2.225864Ni 0.91% 64 x 0.91/100 = 0.5824
58.7541
Atoms, Molecules and Ions
Chemistry 120
The Periodic Table
The Periodic Table is an ordered array of the elements, with rising atomic number.
First written down by Dimitri
Mendeléev as a list of the
elements with increasing atomic
Mass. The elements naturally
grouped themselves by chemical
properties.
Atoms, Molecules and Ions
Dimitri Mendeléev
(1834 – 1907)
Chemistry 120
s block p block1 H
1He2
Atoms, Molecules and Ions
Building the Periodic Table
Chemistry 120
Atoms, Molecules and Ions
Building the Periodic Tables block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
Al13
Si14
P15
S16
Cl17
Ar18
Atoms, Molecules and Ions
Building the Periodic Table
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
Atoms, Molecules and Ions
The Periodic Table
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
Atoms, Molecules and Ions
The Periodic Table
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Atoms, Molecules and Ions
The Periodic Table
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The Periodic Table
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The S block
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The S block and P block
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The S block , P block
and D block
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The S block , P block ,
D block and F block
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The Radioactive elements
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
Gases at room temperature
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
Gases and liquids at room temperature
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The Non-metals
Chemistry 120
General Characteristics of Non-metals
Bad conductors of electricity
- often insulators or semiconductors
- conductivity rises with increasing temperature
Bad conductors of heat
Brittle, not maleable, not ductile
Atoms, Molecules and Ions
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
7 Fr86
Ra88
Lr103
Rf104
Db105
Sg106
Bh107
Hs108
Mt109
110 111 112
f blockLa57
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Ac89
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Atoms, Molecules and Ions
The Non-metals and
The Metals
Chemistry 120
General Characteristics of Metals
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
- d block metals in general better than p block metals
Atoms, Molecules and Ions
Chemistry 120
Dalton and Compound Atoms
Atoms, Molecules and Ions
John Dalton rejuvenated the atomic theory and used the terms compound atoms and atoms to define the basic building blocks of matter.
Dalton’s compound atoms are today’s
MOLECULES
Chemistry 120
Molecules
Atoms, Molecules and Ions
A molecule is a compound where two or more atoms are bound together by sharing the outer electrons in a covalent bond.
Most molecular species are formed by the non-metals
Chemistry 120
Molecules
Atoms, Molecules and Ions
A molecule is a compound where two or more atoms are bound together by sharing the outer electrons in a covalent bond.
Most molecular species are formed by the non-metals
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4Oxygen O2
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4Oxygen O2
Sulfur S8
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4Oxygen O2
Sulfur S8
Fluorine F2
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4Oxygen O2
Sulfur S8
Fluorine F2
Chlorine Cl2
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4Oxygen O2
Sulfur S8
Fluorine F2
Chlorine Cl2
Bromine Br2
Chemistry 120
Elements whose natural forms occur as molecules include
Atoms, Molecules and Ions
B5
C6
N7
O8
F9
Si14
P15
S16
Cl17
Ge32
As33
Se34
Br35
Sb51
Te52
I53
Xe54
Nitrogen N2
Phosphorous P4
Arsenic As4Oxygen O2
Sulfur S8
Fluorine F2
Chlorine Cl2
Bromine Br2
Iodine I2
Chemistry 120
As a molecule is a compound, it has a definite chemical composition and we write a formula for the composition:
Elemental sulfur has the formula
S8
Atoms, Molecules and Ions
Chemistry 120
As a molecule is a compound, it has a definite chemical composition and we write a formula for the composition:
Elemental sulfur has the formula
S8
Atoms, Molecules and Ions
Chemical Symbol
Number of atoms in the molecule
Chemistry 120
Methane CH4
Ethanol C2H6O
Sulfuric Acid H2SO4
Atoms, Molecules and Ions
Chemistry 120
Methane CH4 1 Carbon
4 Hydrogens
Ethanol C2H6O 2 Carbons
4 Hydrogens
1 Oxygen
Sulfuric Acid H2SO4 2 Hydrogens
1 Sulfur
4 Oxygens
Atoms, Molecules and Ions
Chemistry 120
There are several types of formulæ (not formulas)
Empirical formula: The simplest ratio of atoms
Molecular formula: The actual number of atoms in the molecule
Structural formula: The structure and number of atoms in the molecule
Atoms, Molecules and Ions
Chemistry 120
Empirical formula:
Acetic Acid: CH2O
Glucose CH2O
Formaldehyde CH2O
Atoms, Molecules and Ions
Chemistry 120
Empirical formula Molecular
Acetic Acid: CH2O C2H4O2
Glucose CH2O C6H12O6
Formaldehyde CH2O CH2O
Atoms, Molecules and Ions
Chemistry 120
Empirical formula Molecular Structural
Acetic Acid: CH2O C2H4O2
Glucose CH2O C6H12O6
Formaldehyde CH2O CH2O
Atoms, Molecules and Ions
H C
H
C
H
O
O H
OHC C
OH
H
C
H
HO
C
OH
H
C
OH
H
CH2OH
C
O
H H
Chemistry 120
Molecules with the same molecular formula but different structural formulæ are called
ISOMERS
Atoms, Molecules and Ions
Chemistry 120
Molecules with the same molecular formula but different structural formulæ are called
ISOMERS
For C2H6O
Atoms, Molecules and Ions
Chemistry 120
Molecules with the same molecular formula but different structural formulæ are called
ISOMERS
For C2H6O
Atoms, Molecules and Ions
H C
H
C
H
H
O
H
H
Ethanol
Chemistry 120
Molecules with the same molecular formula but different structural formulæ are called
ISOMERS
For C2H6O
Atoms, Molecules and Ions
H C
H
C
H
H
O
H
H
Ethanol
or
Chemistry 120
Molecules with the same molecular formula but different structural formulæ are called
ISOMERS
For C2H6O
Atoms, Molecules and Ions
H C
H
C
H
H
O
H
H
Ethanol
or H C
H
H
C
H
O
H
H
Dimethyl ether
Chemistry 120
Formulæ tell us
the simplest composition of the molecule
empirical formulæ
Or
the actual composition of the molecule
molecular formulæ
Or
the structure and composition of the molecule
structural formulæ
Atoms, Molecules and Ions
Chemistry 120
But the three dimensional structure of the
molecule is best represented using models or a
chemical drawing package (e.g. ChemDraw) as the
reactivity and chemistry of a molecule takes place
in three dimensions
Atoms, Molecules and Ions
Chemistry 120
http://www.sci.ouc.bc.ca/chem/molecule/molecule.html
Capsaicin
CaffeineStrychnine
RDX
Chemistry 120
Writing Formulæ
Prefixes denote the number of atoms
Mono 1 Hexa 6
Di 2 Hepta 7
Tri 3 Octa 8
Tetra 4 Nona 9
Penta 5 Deca 10
Atoms, Molecules and Ions
Chemistry 120
Writing Formulæ
The first element in the name is the one
farthest to the left
and
lowest in the group
Hydrogen and oxygen are sometimes exceptions
Atoms, Molecules and Ions
Chemistry 120
Writing Formulæ
The second name drops the suffix and adds
-ide
instead
chlorine chloride oxygen oxide
Atoms, Molecules and Ions
Chemistry 120
Example
1 phosphorous atoms 5 fluorine atoms
Atoms, Molecules and Ions
Chemistry 120
Example
1 phosphorous atoms 5 fluorine atoms
Phosphorous
Atoms, Molecules and Ions
Chemistry 120
Example
1 phosphorous atoms 5 fluorine atoms
Phosphorous Pentafluor
Atoms, Molecules and Ions
Chemistry 120
Example
1 phosphorous atoms 5 fluorine atoms
Phosphorous Pentafluoride
Atoms, Molecules and Ions
PF5
Chemistry 120
Example S2F10
Atoms, Molecules and Ions
Chemistry 120
Example S2F10
2 sulfur atoms
- disulfur
Atoms, Molecules and Ions
Chemistry 120
Example S2F10
2 sulfur atoms
- disulfur
10 fluorine atoms
- decafluoride
Atoms, Molecules and Ions
Chemistry 120
Example S2F10
2 sulfur atoms
- disulfur
10 fluorine atoms
- decafluoride
disulfur decafluoride
Atoms, Molecules and Ions
Chemistry 120
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
Atoms, Molecules and Ions
Chemistry 120
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, Molecules and Ions
Chemistry 120
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!!!
Atoms, Molecules and Ions
Chemistry 120
Compounds which are made up of ions are called
IONIC
In general they are
hard
brittle
insulators in the solid state but conductors in solution or in the melt
have high melting points and boiling points
Atoms, Molecules and Ions
Chemistry 120
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 but in the s and p block.......
Atoms, Molecules and Ions
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Atoms, Molecules and Ions
Monocations: Li+, Na+, K+, Rb+, Cs+
Monocations
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Atoms, Molecules and Ions
Monocations: Li+, Na+, K+, Rb+, Cs+
Dications: Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Sn2+, Pb2+
Mono- and dications
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Atoms, Molecules and Ions
Monocations: Li+, Na+, K+, Rb+, Cs+
Dications: Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Sn2+, Pb2+
Trications: Al3+, Ga3+
Mono-, di- and trications
Chemistry 120
s block p block1 H
1He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Atoms, Molecules and Ions
Chemistry 120
1 H1
He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Atoms, Molecules and Ions
Trications: Al3+, Ga3+
Mono-, di- and trications
Monocations: Li+, Na+, K+, Rb+, Cs+
Dications: Be2+, Mg2+, Ca2+, Sr2+, Ba2+
Sn2+, Pb2+
Trianions N3-, P3-
Dianions
O2-, S2-
Monoanions
Chemistry 120
Atoms, Molecules and Ions
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+
Chemistry 120
Atoms, Molecules and Ions
These cations and anions are formed from atoms but we can form anions and cations from molecules. These are termed
POLYATOMIC IONS
1 H1
He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
3 Na11
Mg12
d block Al13
Si14
P15
S16
Cl17
Ar18
4 K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
5 Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
6 Cs55
Ba56
Lu71
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Chemistry 120
Atoms, Molecules and Ions
Polyatomic Ions
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 or negative charge.
O
S
OOO
O N
O
O
S
O OO
O
P
OOO
2
23
H
N
HHH
O
HHH
C
C
C CC
CC
H
H
H
HH
H
H
S
H3C CH3
CH3
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
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)
Svante Arrhenius
(1859 – 1927)
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
Acidic and basic solutions are formed by dissolution or by reaction.
Dissolution
- a compound containing hydronium ions, H3O+
(aq) or hydroxide ions, OH- (aq) dissociates and gives an acidic or basic solution
Reaction
- a compound reacts with water to form an acidic or basic solution
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
For an acid A, the reaction is
For a acid B, the reactions are
AH + H2O(l) A-(aq) + H3O+
(aq)
BOH(s)+ H2O(l) B+(aq) + OH-
(aq)
B + H2O(l) BH+(aq) + OH-
(aq)
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
An example of the formation of an acid solution is
HBr(g) + H2O(l) Br-(aq)
+ H3O+(aq)
Chemistry 120
Atoms, Molecules and Ions
HBr(g) + H2O(l) Br-(aq)
+ H3O+(aq)
Water Hydronium
ion
Acids, bases and salts
Water is protonated to form the hydronium ion – hydrogen bromide is a proton donor
Chemistry 120
Atoms, Molecules and Ions
HBr(g) + H2O(l) Br-(aq)
+ H3O+(aq)
Hydrogen Bromide
Water
Bromide
Hydronium
ion
Acids, bases and salts
And the counter ion, necessary for electroneutrality is bromide ion.
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
An example of the formation of a basic solution by dissolution is
NaOH dissolves in water to give sodium ions and hydroxide ions. NaOH is an ionic solid which contains hydroxide ions.
Na+
OH-
NaOH(s) Na+(aq) + OH-
(aq)H2O(l)
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
An example of the formation of a basic solution is
Ammonia reacts with water and removes an H+ to form NH4
+, the ammonium ion,
NH3(g) + H2O(l) NH4+
(aq) + OH-(aq)
Basic solutions are formed by reaction or dissolution – formation of acid solutions by dissolution are very rare.
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
Hydroxide and hydronium ions will react to form water.
The presence of hydroxide and hydronium ions in water is crucial, though in pure water the concentration is very low.
Acids and bases also react to form
SALTS
2H2O(l)H3O+(aq) + OH-
(aq)
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
Salt formation occurs when an acid and a base neutralize each other.
Remember the reaction between hydroxide and hydronium:
HCl(g) + H2O(l) H3O+(aq) + Cl-(aq)
NaOH(s) Na+(aq) + OH-
(aq)H2O(l)
2H2O(l)H3O+(aq) + OH-
(aq)
Chemistry 120
Atoms, Molecules and Ions
Acids, bases and salts
The acid and base neutralize each other to form
water, leaving Na+(aq) and Cl-
(aq) in solution – the
saltNa+
(aq) + OH-(aq) + H3O+
(aq) + Cl-(aq)
Na+(aq) + Cl-(aq) + 2H2O(l)
+
Chemistry 120
Atoms, Molecules and Ions
Common acids and bases
Common acids areAcid Anion(s)
H2SO4 Sulfuric acid SO42-
(aq) and HSO4-(aq)
HX Hydrohalic acids X-(aq)
(X = F, Cl, Br, I)
H3PO4 Phosphoric acid PO43-
(aq), HPO42-
(aq), H2PO4- (aq)
H2CO3 Carbonic acid CO32-
(aq) and HCO3-(aq)
Chemistry 120
Atoms, Molecules and Ions
Common acids and bases
Common Bases areBase Anion(s)
MOH Group IA hydroxides M(aq)+
, OH(aq) -
(M = Li, Na, K, Rb, Cs)
M(OH)2 Group IIA hydroxides M(aq)2+, OH(aq)
-
(M = Mg, Ca, Sr, Ba)
NH3, RNH2, R2NH, R3N NH4+
, RNH3+ OH(aq)
-
R2NH2+ R3NH+
Chemistry 120
Atoms, Molecules and Ions
Introduction to Organic Chemistry
- Hydrocarbons
- Alkanes
- Alkenes
- Alkynes
- Functional groups
- Alcohols - Ethers
- Carboxylic Acids - Esters
Chemistry 120
Atoms, Molecules and IonsOrganic Chemistry is the study of compounds composed of carbon, with H, O, N, P, S and X (X = F, Cl, Br, I). The name stems from the isolation of these compounds initially from living bodies – plants and animals.
In 1828, Friedrich Wohler synthesized urea from ammonium cyanate, organic from inorganic.
C6
N7
O8
F9
Si14
P15
S16
Cl17
Br35
I53
Friedrich Wohler(1800-1882)
[NH4+][NCO-]
O
CH2N NH2Ammonium Cyanate Urea
Chemistry 120
Atoms, Molecules and Ions
Hydrocarbons
Hydrocarbons are the basic compounds of organic chemistry and are simply compounds of carbon and hydrogen.
There are three types
Alkanes Alkenes Alkynes
Alkanes are termed saturated hydrocarbons, whereas alkenes and alkynes are unsaturated.
Chemistry 120
Atoms, Molecules and Ions
Carbon contains four electrons in the outer shell and
can share all four with other atoms or itself.
We say that the valence of carbon is four and so the simplest hydrocarbon is CH4, methane. We draw methane as
1 H1
He2
2 Li3
Be4
B5
C6
N7
O8
F9
Ne10
H
CH H
H
H
CHH
HHH
H
H
C
Chemistry 120
Atoms, Molecules and Ions
The next saturated hydrocarbon or alkane is ethane, C2H6, which has the structure
Followed by propane
H
CH
H
H
CH
HH
C H
H
H
CH
H
H
CH
H
H
C
HH
H
C
H
C
HH
H
C H
H
H
C
H
H
Chemistry 120
Atoms, Molecules and Ions
Important hydrocarbon fragments (which are not molecules)
Methane Methyl Me- CH3-
H
CH
H
H
CH
H
Chemistry 120
Atoms, Molecules and Ions
Methane Methyl Me- CH3-H
CH
H
I
H
CH
H
IMethyl Iodide Me-I
Chemistry 120
Atoms, Molecules and Ions
Methane Methyl Me- CH3-H
CH
H
I
H
CH
H
IMethyl Iodide Me-I
Chemistry 120
Atoms, Molecules and Ions
Methane Methyl Me- CH3-
Methyl Alcohol
Methanol Me-OH
H
CH
H
OH
H
CH
H
OH
Chemistry 120
Atoms, Molecules and Ions
Methane Methyl Me- CH3-
Methyl Alcohol
Methanol Me-OH
H
CH
H
OH
H
CH
H
OH
Chemistry 120
Atoms, Molecules and Ions
Other important hydrocarbon fragments (which are not molecules)
Ethane Ethyl Et- C2H5-
Propane Propyl Pr- C3H7-
Butane Butyl Bu- C4H9-
H
CH
H H
C
HH
C
HH
C
HH
Chemistry 120
Atoms, Molecules and Ions
Isomers in organic chemistry
Every carbon atom has four bonds. With methane,
ethane and propane, there is only one way of
forming the hydrocarbon.
The structural formula is identical to the molecular
formula and there is only one way of writing the
structural formula, consistent with the molecular
formula.
Chemistry 120
Atoms, Molecules and Ions
Every carbon atom has four bonds. With methane, ethane and propane, there is only one way of arranging the atoms.
H C
H
H
H
H C
H
H H
C
H
H
H C
H
H H
C
H
H
C
H
H
H
CH H
H
H
C
HH
H
C
H
H
H
CH
HC
H H
H
C
HH
There is only one structural formula for each molecular formula
Chemistry 120
Atoms, Molecules and Ions
Butane, C4H10, can have more than one structural formula for the molecular formula
There is more than one structural formula for each molecular formula
H C
H
H H
C
H
H
C
H
H
C
H
H
H C
H
H
C
C
H
H
C
H
H
H
HH
Chemistry 120
Atoms, Molecules and Ions
Butane, C4H10, can have more than one structural formula for the molecular formula
There is more than one structural formula for each molecular formula.
THEY ARE ISOMERIC
H C
H
H H
C
H
H
C
H
H
C
H
H
H C
H
HC
C
H
H
C
H
H
H
HH
Chemistry 120
Atoms, Molecules and Ions
Isomers in organic chemistry
Pentane has more isomers.......
H
C HH
H C H
H C H
H C H
H C H
H
H
C HH
C H
H C H
H C H
H
H
C
H
H
H
CH H
C
HCH
H
H
C
H
H
H
C
H
H
Chemistry 120
Atoms, Molecules and IonsIn CnH2n+2, the linear alkanes, the number of isomers rises rapidly with n, the number of carbon atoms CnH2n+2 n Number of Isomers
Butane 4 2
Pentane 5 3
Hexane 6 5
Heptane 7 9
Octane 8 18
Nonane 9 35
Decane 10 75
Dodecane 12 355
Pentadecane 15 4,347
Icosane 20 366,319
Chemistry 120
Atoms, Molecules and Ions
The C-C chain in an
alkane may also be
joined end to end to
form a ring, the cyclic
alkanes. Whereas
linear alkanes have a
formula CnH2n+2, the
cyclic alkanes have a
formula CnH2n.
H2C
H2C
CH2
CH2
CH2
CH2
H2C
H2C CH2
CH2
CH2
H2C
H2C CH2
CH2
H2C
H2C
CH2
Chemistry 120
Atoms, Molecules and Ions
Alkenes and Alkynes
In the alkane series, only one electron per carbon is shared between carbon atoms. This is termed a single bond and contains an electron pair, 1 e- from each C atom.
Ethane
Here red denotes electrons from C and green denotes
electrons from H.
C
H
HH
C
H
HH
C
H
HH
C
H
HH
Chemistry 120
Atoms, Molecules and Ions
Alkenes and Alkynes
In an alkene or alkyne, a C atom shares two electrons with a neighboring atom to form a double bond or triple bond containing 4 or 6 electrons.
Ethene
(Ethylene)
Ethyne
(Acetylene)
C
H
H
C
H
H
C
H
H
C
H
H
CH CH C HC H
Chemistry 120
Atoms, Molecules and Ions
Functional groups
We can expand the number of compounds possible by binding different functional groups to a hydrocarbon fragment such as methyl or ethyl.
Alcohols -OH Alkyl halides -X
Amines -NH2
Chemistry 120
Atoms, Molecules and Ions
Functional groups
Methane Methanol Methylamine Chloromethane
H
CH
H
H
H
CH
H
H
H
CH
H
OH
H
CH
H
OH
H
CH
H
Cl
H
CH
H
Cl
H
CH
H
Cl
H
CH
H
Cl
Chemistry 120
Atoms, Molecules and Ions
Functional groups
Replacing a –CH2– group in an alkane gives an ether
Pentane Diethyl ether
H C
H
H H
C
H
H
C
H
H
C
H
H
C
H
H
H3C
CH2
CH2
CH2
CH3
H C
H
H H
C
H
O
H
C
H
H
C
H
H
H3C
CH2
O
CH2
CH3
Chemistry 120
Atoms, Molecules and Ions
More complex functional groups
Introducing a double bond to oxygen gives a whole series of new classes of compoundsKetonesPentane 3-pentanone 2-pentanone
H C
H
H H
C
H
H
C
H
H
C
H
H
C
H
H
H3C
CH2
CH2
CH2
CH3
H3C
CH2
CH2
C
CH3
O
H C
H
H H
C
H
C
H
C
O
H
C
H
H
H
12345
H C
H
H H
C
H
C
O
H
C
H
H
C
H
H
H3C
CH2
C
CH2
CH3
O
12345
Chemistry 120
Atoms, Molecules and Ions
More complex functional groupsAldehydes
If the C=O function is at the end of the chain, then the compound is termed an aldehydePentane Pentanal
H C
H
H H
C
H
H
C
H
H
C
H
H
C
H
H
H3C
CH2
CH2
CH2
CH3 H3C
CH2
CH2
CH2
C
H C
H
H H
C
H
C
H
C
H
C
O
H
H
H
O
H
Chemistry 120
Atoms, Molecules and Ions
More complex functional groupsCarboxylic acids, esters and amides
These classes of molecules contain the group
C
O
Z Z = -OH, -OR, NR2, -X
Chemistry 120
Atoms, Molecules and Ions
More complex functional groupsCarboxylic acids, esters and amides
Z varies according to
C
O
OH
C
O
OR
C
O
NR2Carboxylic acid
Carboxylic Ester
Carboxylic Amide
C
O
X Carboxylic Acid Halide