seen above that the atoms are placed in a crystalline solid regularly and periodically. This restriction means that there are only a few possible networks.
A 3-dimensional solid there are only 14 different networks, grouped into 7 sets. The networks are described by unit vectors (a, b, c) establishing the frequency in each direction, as well as the relative direction or angles formed between them (a, b, g)
The most general is triclinic, as it is different from one another both angles, as the vectors that define the network. However, most common methods, while simple, are the cubic and hexagonal.
The cubic, as its name suggests, is a cube with equal frequency in all three directions, and angles of 90 º. Examples are common salt (sodium chloride, NaCl), silicon (Si), or diamond (carbon, C)
The hexagonal system has two vectors forming an angle of 120 degrees, and the third 90 degrees. This form is a hexagonal prism, and corresponds to materials such as graphite (carbon, C), or sapphire (also called alumina, Al2O3)
The cubic lattice
The simplest base is to place an atom in one corner a cube:
This type of network is called simple cubic lattice (SC), and has only one point in the network before it. In forming the crystal lattice, the atoms of adjacent cells round the corners of the cube. The position of the lower left corner, foreground, is usually considered the origin of coordinates of the unit cell. Thus, the coordinates of this point of network would be (0,0,0). Despite its simplicity, there are many elements that crystallize in this way.
The second type of cubic lattice is called body-centered cubic (Body-Centered Cubic, BCC). In this case, there are two occupied grid points, which are a corner and the center of the cube:
In this case, the two network points are at coordinates (0,0,0) and (a / 2, a / 2, a / 2), being to the lattice parameter or the length of the edge of the cube of the unit cell. Examples of materials that are BCC lattices is brass (CuZn, a = 2.94 å). Cu atom is placed in the corner, while Zn occupies the center of the body. That is, the unit cell contains 1 atom of copper, zinc and 1.
The final structure is cubic face-centered (Face Centered Cubic, FCC). Network has 4 points, one in the corner, and three more in the faces of the cube.
the coordinates of the grid points are (0,0,0), (0, a / 2, a / 2), (a / 2.0, a / 2) and (a / 2 , a / 2.0). A well-known network of this type is sodium chloride (common salt, NaCl), a = 5.63 å). Unlike brass, this time each lattice point is occupied by one atom of each class, but by a molecule of NaCl, so that each unit cell contains 4 atoms of Na, Cl and 4
FCC Network Other examples are the silicon (Si) or gallium arsenide (GaAs), each with its own peculiarities in its structure, widely used in microelectronics. The
hexagonal lattice
Of all the networks, there are two that offer maximum possible compaction. The first is the FCC. The other is the hexagonal close-packed.
hexagonal network is composed of three vectors a, b, c, to satisfy a = b, with an angle of 120 ° and the angle between a and b to c is 90 °. The maximum compaction is achieved when c = 1,633 • a. The base is formed by two atoms, the first located at the origin (0,0,0), and the other positions (2a / 3, / 3, a / 2)
A 3-dimensional solid there are only 14 different networks, grouped into 7 sets. The networks are described by unit vectors (a, b, c) establishing the frequency in each direction, as well as the relative direction or angles formed between them (a, b, g)
The most general is triclinic, as it is different from one another both angles, as the vectors that define the network. However, most common methods, while simple, are the cubic and hexagonal.
The cubic, as its name suggests, is a cube with equal frequency in all three directions, and angles of 90 º. Examples are common salt (sodium chloride, NaCl), silicon (Si), or diamond (carbon, C)
The hexagonal system has two vectors forming an angle of 120 degrees, and the third 90 degrees. This form is a hexagonal prism, and corresponds to materials such as graphite (carbon, C), or sapphire (also called alumina, Al2O3)
The cubic lattice
The simplest base is to place an atom in one corner a cube:
This type of network is called simple cubic lattice (SC), and has only one point in the network before it. In forming the crystal lattice, the atoms of adjacent cells round the corners of the cube. The position of the lower left corner, foreground, is usually considered the origin of coordinates of the unit cell. Thus, the coordinates of this point of network would be (0,0,0). Despite its simplicity, there are many elements that crystallize in this way.
The second type of cubic lattice is called body-centered cubic (Body-Centered Cubic, BCC). In this case, there are two occupied grid points, which are a corner and the center of the cube:
In this case, the two network points are at coordinates (0,0,0) and (a / 2, a / 2, a / 2), being to the lattice parameter or the length of the edge of the cube of the unit cell. Examples of materials that are BCC lattices is brass (CuZn, a = 2.94 å). Cu atom is placed in the corner, while Zn occupies the center of the body. That is, the unit cell contains 1 atom of copper, zinc and 1.
The final structure is cubic face-centered (Face Centered Cubic, FCC). Network has 4 points, one in the corner, and three more in the faces of the cube.
the coordinates of the grid points are (0,0,0), (0, a / 2, a / 2), (a / 2.0, a / 2) and (a / 2 , a / 2.0). A well-known network of this type is sodium chloride (common salt, NaCl), a = 5.63 å). Unlike brass, this time each lattice point is occupied by one atom of each class, but by a molecule of NaCl, so that each unit cell contains 4 atoms of Na, Cl and 4
FCC Network Other examples are the silicon (Si) or gallium arsenide (GaAs), each with its own peculiarities in its structure, widely used in microelectronics. The
hexagonal lattice
Of all the networks, there are two that offer maximum possible compaction. The first is the FCC. The other is the hexagonal close-packed.
hexagonal network is composed of three vectors a, b, c, to satisfy a = b, with an angle of 120 ° and the angle between a and b to c is 90 °. The maximum compaction is achieved when c = 1,633 • a. The base is formed by two atoms, the first located at the origin (0,0,0), and the other positions (2a / 3, / 3, a / 2)
Annex
Diamonds and pens
Structure
crystalline architecture 
