#versatilenatureofcarbon #allotropesofcarbon #10thclasschemistry

The phenomenon by which an element can exist in more than one physical state is called allotropy. The allotropes of carbon can be categorized into two:

Amorphous Carbon Allotropes
Crystalline Carbon Allotropes
What are Allotropes of Carbon?
Carbon with atomic number 6 and represented by the symbol ‘C’ in the periodic table is one of the most influential elements we see around us. Carbon is one of the elements which shows allotropy. The allotropes of carbon can be either amorphous or crystalline (Diamond, Graphite).

Graphite
It is also a pure form of carbon. This allotrope of carbon is composed of flat two-dimensional layers of carbon atoms which are arranged hexagonally. It is a soft, black and slippery solid. This property of graphite persists because it cleaves easily between the layers.

In each layer, each C atom is linked to three C atoms via a C-C covalent bond. Each carbon here is sp2 hybridized. The fourth bond is formed as a pi bond. Since the π-electrons are delocalized, they are mobile and can conduct electricity.

Graphite is of two forms: α and ß.

In α form, the layers are arranged in the sequence of ABAB with the third layer exactly above the first layer.

In the ß form, the layers are arranged as ABCABC.

Properties of Graphite:
Since the layers are stacked over each other, this carbon allotrope can act as a lubricant.
It also has metallic lustre which helps in the conduction of electricity. It is a very good conductor of both heat and electricity
One of the most important properties of graphite is that it is used as a dry lubricant for machines at high temperature where we cannot use oil.
Graphite is used to make crucibles which have the property that they are inert to dilute acids as well as to alkalis.

Diamond
It is the purest crystalline allotrope of carbon. It has a number of carbons, linked together tetrahedrally. Each tetrahedral unit consists of carbon bonded to four carbon atoms which are in turn bonded to other carbons. This gives rise to an allotrope of carbon having a three-dimensional arrangement of C-atoms.

Do you know why a Diamond is Hard?
It is hard because breaking a diamond crystal involves rupturing many strong covalent bonds. Breaking covalent bonds is no easy task. This property makes this carbon allotrope the hardest element on earth.

Physical Properties of Diamond
It is extremely hard
It has a very high melting point
It has a high relative density
It is transparent to X-rays
It has a high value of the refractive index
It is a bad conductor of electricity
It is a good conductor of heat
It is insoluble in all solvents