2.2 Covalent Bonds
23
Fig. 2.2 Octet, the favorite card game of the ‘Atomis’ (trying to reach octet configuration in a bond by swapping
wavefunctions). The bubble says: ‘Do you have a 2p?’. Reprinted with permission from [171], ©2002 Wiley-VCH
(a)
-1 0
1
-1
0
1
-1
0
1
(b)
-2 -1 0 1
2
-1
0
1
-1
0
1
(c)
-1
0
1
-2
-1
0
1
2
-1
0
1
(d)
0
1
-1
0
1
-1
0
1
(e)
2s
2p x
2p y
2p z
2s
2p x
2p y
2p z
(f)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
2
(g)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
(h)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
(i)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
2
2
2
-1
Fig. 2.3 a s orbital, b, c, d p x , p y and p z orbital, e hybridization, f, g, h, i orbitals of the sp 3 hybridization: f
(s+p x +p y +p z )/2, g) (s+p x −p y −p z )/2, h (s−p x +p y −p z )/2, (i) (s−p x −p y +p z )/2
In Fig. 2.4a the energy of a crystal made up from silicon atoms is shown for various crystal structures
2
or phases (cf. Chap. 3). We note that the crystal energy of further silicon structures are discussed in
[175]. The lattice constant with the lowest total energy determines the lattice spacing for each crystal
structure. The thermodynamically stable configuration is the phase with the lowest overall energy for
given external conditions.
The covalent bond of a group-IV atom to other group-IV atoms has a tetrahedral configuration
with electron-pair bonds, similar to the hydrogen molecule bond. In Fig. 2.4b the energy states of the
n = 2 shell for tetrahedrally bonded carbon (diamond, see Chap. 3.4.3) are shown as a function of
2 Hexagonal diamond is wurtzite structure with identical atoms in the base.
23
Fig. 2.2 Octet, the favorite card game of the ‘Atomis’ (trying to reach octet configuration in a bond by swapping
wavefunctions). The bubble says: ‘Do you have a 2p?’. Reprinted with permission from [171], ©2002 Wiley-VCH
(a)
-1 0
1
-1
0
1
-1
0
1
(b)
-2 -1 0 1
2
-1
0
1
-1
0
1
(c)
-1
0
1
-2
-1
0
1
2
-1
0
1
(d)
0
1
-1
0
1
-1
0
1
(e)
2s
2p x
2p y
2p z
2s
2p x
2p y
2p z
(f)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
2
(g)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
(h)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
(i)
-2 -1 0 1
-2
-1
0
1
-2
-1
0
1
2
2
2
2
2
-1
Fig. 2.3 a s orbital, b, c, d p x , p y and p z orbital, e hybridization, f, g, h, i orbitals of the sp 3 hybridization: f
(s+p x +p y +p z )/2, g) (s+p x −p y −p z )/2, h (s−p x +p y −p z )/2, (i) (s−p x −p y +p z )/2
In Fig. 2.4a the energy of a crystal made up from silicon atoms is shown for various crystal structures
2
or phases (cf. Chap. 3). We note that the crystal energy of further silicon structures are discussed in
[175]. The lattice constant with the lowest total energy determines the lattice spacing for each crystal
structure. The thermodynamically stable configuration is the phase with the lowest overall energy for
given external conditions.
The covalent bond of a group-IV atom to other group-IV atoms has a tetrahedral configuration
with electron-pair bonds, similar to the hydrogen molecule bond. In Fig. 2.4b the energy states of the
n = 2 shell for tetrahedrally bonded carbon (diamond, see Chap. 3.4.3) are shown as a function of
2 Hexagonal diamond is wurtzite structure with identical atoms in the base.