Sodium chloride,Cesium chloride,Hexagonal close packed,diamond structure

Sodium Chloride

1. Sodium chloride, also known as salt,is an ionic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean.It is  obtained through the evaporation of seawater which can be used in cookin.See figure 1 :

2. The United States had been the world’s leading salt producer until 2005, when it was surpassed by China.In 2010, the top five producers (in million tonnes) being China (60.0), United States (45.0), Germany (16.5), India (15.8) and Canada (14.0).

Figure 1 : Sea salt harvesting in pak thale thailand

3. Sodium chloride forms crystals with face-centered cubic symmetry.See figure 1 :

 Figure 2 :  The structure of crystalline salt.The bigger spheres are chlorine.The smaller spheres are sodium. 

Cesium Chloride 

1. Cesium is nature’s most alkaline mineral.  When formed into salt, it becomes cesium chloride.In many cancer treatment,and even in most advanced stage of it, cesium chloride is one of the recommended drugs to use.

2. Among the ability of cesium chloride is to raise the pH of the cell to 8.0. This creates an environment that is fatal to the cancer cells.  In a matter of hours, the cell dies.cesium chloride does not affect normal cells.  It only targets the cancer cells.  At the same time, cesium chloride can stop pain by neutralizing weak lactic acid.  This happens within 12 to 24 hours.The structure of cesium chloride ,as in figure below :

Hexagonal close packed

1. In a hexagonal close packed,arrangement of atoms,the unit cell consists of three layer of atoms.There are,at the top,bottom and the middle layer.The top and bottom layers consists of six atoms at corner of hexagon,and one atom at the center of each hexagon.While the middle layer contains three atoms located between the top and the bottom.See figure below.

 Diamond

1. Diamond was form from the carbon atoms are arranged in a variation of the face-centered cubic crystal structure.

2. Diamond has the highest hardness and thermal conductivity of most material .This is due to its strong covalent bond that exist within its system.

3.Diamond and graphite,bothe made up of carbon atom. In diamond we have the hardest known material, in graphite we have one of the softest, simply by rearranging the way the atoms are bonded together. 

4. How make the diamond harder than graphite?This is because,diamond has a more complex structure. Diamond's structure is like many pentagons connected together, each pentagon sharing a side with another pentagon or each pentagon sharing a point with another pentagon. All the points are linked together in some way. 

  While,graphite's atoms are arranged in sheet-like structures that can slide over each other easily .Diamond has tetrahedral-like atomic structure,do refer figure below :

   

Atomic packing factor ( SC,BCC,FCC)

 

Credit : http://www.ecr6.ohio-state.edu

Miller Indices of plane

Figure 1 :

A set of three integers (x y z) are used to represent the orientation of an atomic plane in a cubic of unit cell.These are called miller indices.See the figure,the three coordinates (100),(010),(001) can simply write as < 100 >.OR. <100> is equivalent to (100),(010),(001)

How to determine miller indices (plane) ? See figure below

Miller Indices of directions ( part 2 )

Figure 1 : determine every axis and signs

Figure 2 : every lattice point has their own particular coordinates

Figure 3 : Miller Indices for direction 1

Figure 4 : Miller Indices for direction 2

wigner seitz method 2d

It is a method to find primitive cell.It can be done as follows :

1. Choose lattice point

2. Connect each lattice point to its neighbour.

3.At the midpoint,and normal to these point,draw new lines .Example below :

Miller Indices ( part 1 )

 

Example above :  In this case,the plane intercepts the a axis at one unit length and also the c axis at one unit length. The plane however, never intersects the b axis. In other words, it can be said that the intercept to the b axis is infinity.

 

Credit : Wikipedia,http://www.gly.uga.edu

Unit cell,crystal structure,Primitive cell and Bravais lattice.

1. A unit cell,is one that we repeat to form a perfect single crystal.A unit cell,must be same to the other unit cell : See figure below ,for unit cell in 2D

Figure 1

example a unit cell

 

Figure 2

example of unit cell that construct a full crystal.Observe carefully the repeating pattern of the unit cell.

 

Figure 3

its not necessary for us to construct unit cell starting from the left/right most side 

 Figure 4
we can also construct sets of unit cell by using this way

2. Crystal structure = crystal lattice ( kekisi ) + basis ( a group of atoms that describe crystal structure ).See figure 5

Figure 5

3. Primitive cell ,it is a simple cell ( simple cubic).See figure 6 :

Figure 6

4. Non primitive cell,example,Face CC,Body CC etc (see figure 7 and 8)

 Figure 7

Figure 8

  5.Bravais ( the name of the founder Auguste Bravais ) concluded that,there are only 14 possible space lattice.There are :

     

    Now,we will go 1 by 1,to see the properties of the bravais lattice.From all the     structures given above,we may categorized it into several group,

    a. Cubic crystal - simple cubic,body centered cubic (BCC),Face centered cubic (FCC)

    b. Tetragonal crystal - Simple tetragonal,body centered tetragonal

    c.  Orthorhombic crystal - Simple orthorhombic,BCC orthorhombic,FCC orthorhombic,End centered orthorhombic

    d.  Hexagonal crystal - Simple hexagonal

    e.  Rhombohedral crystal - Simple rhombohedral

    f.  Monoclinic crystal - Simple monoclinic,end centered monoclinic

    g. Triclinic crystal - Simple triclinic

Now,consider the vector a,b and c (refer figure below) is applicable for  not only  simple cubic,but also for the rest of bravais crystals.

 1.cubic crystal, a = b = c,
where angle alpha (angle between vector c and b),beta (angle between a and c ),gamma (angle between vector a  and b )= 90


2.Tetragonal crystal, a = b # c / 
   alpha = beta = gamma = 90 


3.Orthorhombic crystal, a # b # c / 
   alpha = beta = gamma = 90

4.Hexagonal crystal,a = b # c /
   alpha = Beta = 90,while gamma = 120


5.Rhombohedral crystal,a = b = c
   alpha # beta # gamma # 90


6.Monoclinic crystal,a # b # c
   alpha # 90, beta & gamma = 90


7.Triclinic crystal,a # b # c
    alpha # beta # gamma # 90

Crystal structure ( crystalline,polycrystalline and amorphous)

1.Solid material

a.Crystalline - crystalline is a solid material whose constituent atoms, molecules, or ions that  arranged in an orderly repeating pattern .Example,Quartz. The process of forming a crystalline structure from a fluid is a  crystallization / solidification process. 

 Figure 1

 Figure 2

    b.Polycrystalline - Polycrystalline materials are solids that are composed of many crystallites / grains of varying size and orientation

   c.Amorphous – Example of amorphous is glass,opal.It is considered as non-crystalline solid material.Atoms are not orderly repeating pattern.

  

Figure 3

 

Figure 4

Opal is an amorphous,refer figure 5

Opal (figure 5)

Observe the structure f this material,and compare to that of crytalline :

Figure 6

(Left is a crystall structure of quartz (crystalline),right the crystal structure of opal (amorphous)

Note : The difference between quartz ( crystalline solid) and glass (non crystalline solid) : the quartz have an orderly crystalline network,while the glass do not.