In the abstract, there are three allotropes of pure carbon, namely, diamond, graphite, and fullerenes. As a result, graphite and diamond are the two most significant crystalline forms of carbon. Over and above, the chemical properties of both compounds are the same, and it is soot or carbon black in appearance.
Diamond vs Graphite
The main difference between Diamond and Graphite is that Diamond has a crystalline lattice, where the atoms of carbon are arranged in a three-dimensional symmetry within the crystal. Meanwhile, graphite has a layered structure, where rings of six carbon atoms are arranged in a spaced horizontal sheet. Plus, diamond is a hard substance, while graphite is soft.
Diamond is a solid crystalline form of the element carbon in nature. There are four carbon atoms covalently bonded to each other within the diamond structure, making it quite large. Due to the covalent bonding, a lot of energy is required to separate atoms from one another. And for this reason, diamond is widely known as one of the hardest materials in nature.
Meanwhile, graphite is a layer structured allotrope of pure carbon. It is mostly found as a grey crystalline mineral that occurs in some rocks. A sigma bond is formed between each carbon atom in graphite. Since the graphite is bonded in this way, it is soft and easy to break.
Comparison Table Between Diamond and Graphite
| Parameters of Comparison | Diamond | Graphite |
| Definition | In nature, a diamond is a solid, colorless, and clear crystalline form of carbon. | Graphite is an allotrope of pure carbon that is mostly found in between rocks. It is considered minerals in nature. |
| Structure | The structure of diamond is a crystalline lattice. It is a three-dimensional crystal in which the carbon atoms are arranged in symmetry. | The structure of graphite is layered, where carbon atoms are bonded to each other by sigma bonds. |
| Hybridization | There is a total of four carbon atoms in a diamond that are sp3 hybridized and all are bonded together via sigma bonds. | Here, in graphite, each atom is bonded by sp2 hybridization and a sigma bond plays the main role by binding the atoms together. While the unpaired atom forms a pi bond. |
| Geometrical structure | Due to the four bonded carbon electrons, the diamond has a tetrahedral structure. | Due to three bonded carbon electrons, the graphite has a planar geometry structure. |
| Uses | Used as a material in jewelry making, and drilling. | Used as dry cells, electric arc, lubricant, and pencil leads. |
What is Diamond?
Diamond, a naturally existing hardest element, is an allotrope of the element carbon. There are four carbon atoms covalently bonded to one atom through sigma bonds, making it a very complex substance. In diamonds, separating atoms from one another is extremely difficult because of covalent bonding. So, the fact that diamonds are one of the hardest natural materials adds to their reputation instinctively.
The earliest diamonds ever discovered were in India in the fourth century. And soon after, a majority of these gems were exported to various countries resulting in a great bond between India and other nations.
Meanwhile, the bond between the four carbons is of sp3 hybridization. As diamonds have four electrons bonded together to one atom, they have a tetrahedral structure. Diamond is a crystal lattice made up of symmetry-arranged carbon atoms in a three-dimensional structure.
Furthermore, diamond has an impressive amalgamation of physical, chemical, and mechanical characteristics, these include hardness, low coefficient of friction, thermal conductivity, electrical resistance, low thermal expansion coefficient, and strength, the material should also be chemically resistant, biocompatible, and reflect ultraviolet and infrared.
Because of their durability and luster, diamonds are widely used in jewelry. In addition to that, because of their hardness, they are also used to cut, grind, or drill other materials.
What is Graphite?
Meanwhile, graphite is a layer structured allotrope of pure carbon. It is primarily found as a grey crystalline-like mineral that occurs in some rocks. A sigma bond binds three carbon atoms to one another in graphite. Because graphite is bonded this way, it is soft and easily broken. To put it in simple words, due to van der Waals forces, the covalent bonds are easy to break, eventually making the graphite a soft material.
Graphite consists of four carbon atoms that are of sp2 hybridization, each of which is bonded to three of the others via sigma bonds. Meanwhile, the odd atom forms a pi bond. The history of graphite goes back to Cumbria in northern England at the beginning of the sixteenth century. However, initially, it was mistaken as coal, however, when it was heated, it didn’t burn, eventually, resulting in the discovery of graphite.
Over and above, the planar geometry structure of graphite results from three bonded carbon electrons. The properties of graphite incorporate high melting point, soft, slippery greasy feel, insolubility in water and other organic substances, lustrous, opaque, black substance.
Besides, graphite is used in pencils and lubricants, and due to its high conductivity, it is also used in electronic products such as electrodes, batteries, and solar panels.
Main Differences Between Diamond and Graphite
- Diamond is naturally occurring hardest element, whereas, on the other hand, graphite is also a naturally occurring mineral, but becomes economical graphite only through manufacture.
- Diamond is the hardest substance, while graphite is soft and greasy to touch material.
- The hybridization of carbon atoms in diamond is sp3, while, in graphite, the hybridization of carbon atoms is sp2.
- Diamond is a transparent and colorless substance, while graphite is opaque and black in color.
- The relative density, as well as the refractive index of diamond, is higher than the relative density and refractive index of graphite.
- Diamond acts as a good insulator of heat and electricity, whereas graphite has a good conductivity for heat and electricity.
- Diamond has four covalent bonds around one carbon atom, while, in the case of graphite, it has three covalent bonds around one carbon atom.
Conclusion
On the whole, both graphites and diamonds are famous allotropes of the element carbon; where diamonds are hard naturally occurring substances, which are transparent, and widely used in jewelry making and cutting, grinding, or drilling other less hard substances. Meanwhile, on the other hand, graphites are naturally occurring minerals primarily found in rocks, and are opaque and black in appearance during their manufacturing period. The most common use of graphite is in pencil leads and electric cells due to their soft feel and high conductivity respectively. From melting point to relative density, hardness, low coefficient of friction, thermal conductivity, electrical resistance, low thermal expansion coefficient, and strength, both graphite and diamond are specialized in their own ways.
References
- https://www.nature.com/articles/176051a0
- https://inis.iaea.org/search/search.aspx?orig_q=RN:13661340