Page 72 - Science at the nanoscale

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RPS: PSP0007 - Science-at-Nanoscale
June 12, 2009
From Atoms and Molecules to Nanoscale Materials
62
e
H
H
N
O
C
L
Be
B
i
F
N
e
Al
N
Ar
Mg
P
l
C
S
a
Si
C
e
G
K
Kr
n
Z
N
V
i
a
a
u
Se
Sc
T
Br
C
C
o
As
G
e
r
C
F
i
Mn
b
r
R
h
Z
Pd
Y
N
R
Ag
Mo
e
Sb
b
Sn
e
X
c
T
I
Sr
C
u
d
T
n
I
R
R
e
s
Bi
Pb
T
Po
R
n
At
l
I
r
O
Pt
H
g
Au
a
W
T
f
L
H
C
s
a
Ba
f
R
H
a
F
r
Mt
Ac
R
b
s
D
Bh
Sg
o
n
H
t
h
y
T
D
a
L
Er
L
u
d
s
e
i
n
a
m
Yb
T
b
Eu
C
N
d
G
e
Pm
Sm
Pr
d
m
Pa
m
e
d
Es
U
L
i
T
Am
r
o
Md
Pu
N
F
h
s
N
f
C
Bk
p
Act
i
n
C
Figure 4.1.
A simplified Periodic Table of Elements.
Table 4.1 Orbital representation and the quantum numbers.
Name and Symbol
Orbital Representation
Allowed Values
1, 2, 3, . . .
Energy & size of orbital
Principal quantum
number (n)
Shape of orbital (s, p, d, f , . . .)
Angular momentum
0, 1, 2, . . . (n–1)
and the orbital angular
quantum number (l)
momentum
Orientation of the orbital
Magnetic quantum
0, ±1, ±2, . . . , ±l
angular momentum (e.g. p x ,
number (m )
l
p y , p z )
1
Periodic Table of Elements (Fig. 4.1) . In the layout of the Periodic
Table, each horizontal period and each vertical group of elements
have specific related properties as a consequence of the way their ch04
electrons are arranged among the energy states (i.e. their electron
configurations).
In Chapter 3, we learn that the energy states of electrons are
completely characterised by the set of quantum numbers (n, l, m ,
l
m s ). Chemists often use the concept of atomic orbital (AO) to rep-
resent these energy states. Thus, each AO is characterised by a set
of three quantum numbers (n, l and m ). An electron which has
l
either spin up or down and described by the corresponding set (n,
l, m , m s ) is said to “occupy” that particular AO (Table 4.1).
l
1 The readers may refer to a Periodic Table put up on the web e.g.: http://www.-
webelements.com/