Is Diamond a Carbon?

 

Yes, it is an allotrope of carbon.

 

Carbon is significant to the human body and other living things, and it is the second most common element in the human body [1] It is also a key element of many biological molecules (molecules used in life).

 

(Image source shutter stock)

Well-known allotropes of carbon include graphite, diamond, amorphous carbon, and fullerenes. The physical properties of carbon vary widely with the allotropic form of carbon.

We all know that carbon has four electrons in its outer shell. Therefore, carbon can form up to four covalent bonds with other atoms.

 

Do you remember what a covalent bond is?

 

A covalent bond is a shared pair of electrons. Carbon is found with four bonds because forming four covalent bonds means it has eight valence electrons. This way it acquires the electron configuration of a noble gas, which is a stable arrangement.

 

Sketching pencils, cotton t-shirts, and energy drinks are all made primarily of carbon.

 

Facts about carbon:

 

• Carbon is a solid 
• Not transparent as diamond and black as graphite. 
• Carbon appears in different forms, such as soot, coal, graphite, and diamond. 
• It also is the main element of life, making up about 18.5% of the human body!
• Chemical symbol: C
• Atomic number: 6
• Atomic mass: 12

Carbon is the sixth most abundant element, with three naturally occurring isotopes.

•  Carbon-14 is a radioactive isotope that exists in all living tissues. 

By measuring the amount of carbon-14 present in an object, we can calculate the age of the object. 

• Carbon is present in carbon dioxide and carbon monoxide.
• During photosynthesis, plants absorb Carbon dioxide.
• Solid form is also known as dry ice.

Carbon monoxide is a poisonous, colorless, and odorless gas. Carbon is such a crucial part of life that there is an entire field of chemistry, organic chemistry, the study of carbon and carbon-containing compounds, structures, and their reactions. 

 

What are the essential conditions for the formation of diamonds?

• The presence of a temperature of about 2200 degrees Fahrenheit and extreme pressure.
• These factors force the carbon atoms to organize in a networking form and form a tetrahedral phase.
• So, carbon atoms undergo a phase transformation.  

It is also a key element of many biological molecules (molecules used in life).

 

Diamonds form deep within the earth, called the mantle. The mantle is the layer between the earth's crust and outer core. (The layer between the earth's crust and super-heated core). Down there, the intense pressure changes the molecular structure of carbon by compressing the atoms and forcing them into lattice-like structures that we observe in diamonds. Applying pressure of 45-60 kilo bars under temperature conditions up to 1300 degrees Celsius is the natural process through which the diamond forms in the earth's mantle. The basic unit of a diamond is called the unit cell. The basic units in all directions in space, create the crystal that we know as a diamond, the tight tetrahedral arrangement of the carbon atoms in the diamond structure.

The tetrahedral  arrangement of carbon atom

Diamonds were carried upwards from the mantle towards the earth's surface by the lava originating in deep volcanic eruptions. These violent volcanic eruptions happened billions of years ago when the earth was much hotter. 

Lava during a volcanic eruption

Lava from these violent eruptions traveled toward the earth's surface through vertical structures breaking the earth's crust. This magma brought with its mantle rocks, including volcanic rocks, is called kimberlite. These volcanic eruptions cooled upon reaching the earth's surface. The vertical tunnel through which the magma travels to the earth's crust is called a kimberlite pipe. Inside these kimberlite rocks, we find the diamond, that was formed millions of years ago in the earth's mantle.

Depending on the condition under which the diamonds formed, they can have different colors. Diamonds have different colors either because of impurities trapped in the diamond structure or because of certain defects in the lattice or because of the effect of radiations on diamonds.

 

Do you know what magma is?
 
We can see magma beneath the surface of the Earth. Besides molten rock, magma may also contain suspended solid crystals and gas bubbles. [2]
As magma approaches the surface and the overburden pressure drops, dissolved gases bubble out of the liquid so that magma near the surface consists of materials in solid, liquid, and gas phases. [3]

Magma can be found in the mantle or molten crust. (image source Wikipedia)

 
So, what is the difference between magma and lava?
 

• ·         Scientists use the term magma for molten rock that is underground.
  
• ·          Lava is the molten rock that breaks through the Earth's surface.
  

 
Are diamonds a girl's pretty friend?
 
Yes, they are. Wearing a diamond, whether in the form of an engagement ring or any other piece of jewelry, is a pleasure, and that makes you happy.
 
The only material known to be able to cut a diamond is another diamond.
Diamonds are perfect for the jewelry industry because they will maintain their polish for a long time.
 

Diamond ring

• So next time you admire beautiful diamond jewelry, remember that it is a gemstone formed through reactions, that took place billions of years ago deep beneath the earth's surface. That is a pretty ancient and expensive piece of heritage we have from our planet.

 

To learn more about our planet, please read the article: https://retnacpn.blogspot.com/2023/11/know-planet-where-we-live.html

  Structure of Diamond

 A giant lattice of carbon atoms joined together by four covalent bonds forms a diamond. It is hard and strong with a high melting point.

 

• ·         A lattice is a repeating arrangement of atoms, ions, or molecules.

 Carbon atoms of a diamond are bound together by strong covalent bonds with that of the four other carbon atoms, thus making a perfect tetrahedron structure throughout the crystal. The bond lengths of the carbon-carbon atom are equal. It is a three-dimensional network of strong covalent bonds.

These bonds have equal strength in all directions. So, a diamond is hard. There are no free electrons to wander through the structure, making diamonds excellent insulators.

The brilliance of cut diamonds is due to a very high index of refraction (2.42). We know that the refractive index of a material is the ratio of the speed of light in a vacuum (c) to the speed of light in the medium (v). Here, 2.42= c/ v. Hence, v=c/2.42 = 3*10^8/2.42 =1.24*10^8m/s. The main reason for brilliance is the total internal reflection inside the diamond. 

 

Physical Properties of Diamond:

 

Diamond, having nearly twice the density of graphite. Here, each atom is bonded tetrahedrally to four others, forming a 3-dimensional network of atoms.

• The melting point is very high (almost 4000°C).
• Carbon-carbon covalent bonds are strong. 
• Hard due to covalent strong bonds operating in 3-dimensions.
• Do not conduct electricity. All the electrons are held tightly between the atoms and are not free.
• Insoluble in water and organic solvents. 
• The diamond is highly transparent. 
• Diamond is the hardest naturally occurring material known. 
• Diamond has a low electrical conductivity.
• Diamond is hard. Synthetic nanocrystalline diamond is the hardest.[4]
• Diamond is the ultimate abrasive.
• Diamond is an excellent electrical insulator. [5] It has the highest breakdown electric field of any known material.
• Diamond is the best-known naturally occurring thermal conductor.
• Diamond crystallizes in the cubic system.

 

Now, what happens to diamonds when subjected to very high temperatures?

 

Diamonds will turn into graphite, and diamonds can burn up in a house fire.

Under some conditions, carbon crystallizes as ionsdaleite, a hexagonal crystal lattice with all atoms covalently bonded and properties similar to those of diamond. [6]

 

 

Structure Graphite:

 

Sheets of carbon atoms, each joined by three covalent bonds, form the graphite. Spare electrons are above and below each carbon sheet, making graphite soft, flaky, and a good conductor of electricity.

 

Graphite specimen (image source Wikipedia)

Facts about graphite:

 

• The graphite is opaque and black.
• Graphite is soft enough to form a streak on paper.
• Graphite is a good conductor.
• Graphite is the most thermodynamically stable form at standard temperature and pressure.
• Graphite is one of the softest materials known.
• Graphite is a good lubricant. [7]   
• Graphite is a conductor of electricity.[8]  

Some graphite varieties are thermal insulators (firebreaks and heat shields), but some are good thermal conductors.

• Graphite is opaque.
• Graphite crystallizes in the hexagonal system.[9]         

Amorphous carbon is completely isotropic. Carbon nanotubes are among the most anisotropic materials known.

• Graphite, with clay, is in pencils.

Graphene:

A single thinnest sheet of graphite is called graphene, one atom thick. The properties of graphene are similar to that of graphite. 

• It is a great conductor of electricity.
• It has low density.
• It is flexible. 

In the future, we might find wearable electronics made from graphene embedded in our clothing. We currently use it for drug delivery and solar panels.[10]

 

Fullerene:

 

Another allotrope of carbon is fullerene, whose molecules consist of carbon atoms connected by single and double bonds to form a closed or partially closed mesh.

• The closed fullerenes C60 are also informally called buckyballs for their resemblance to the standard soccer ball.

Nested closed fullerenes have been named bucky onions. Cylindrical fullerenes are also called carbon nanotubes or buckytubes.

To learn more about soccer ball design, please read my other article. Why Does a Soccer Ball Have Patterns of Pentagons and Hexagons on Its Surface? https://retnacpn.blogspot.com/2024/02/why-does-soccer-ball-have-patterns-of.html

 

Amorphous carbon:

 

Amorphous carbon is free, reactive carbon that has no crystalline structure. 

 

For further reading:

 

https://retnacpn.blogspot.com/2024/02/why-does-soccer-ball-have-patterns-of.html

https://retnacpn.blogspot.com/2023/11/know-planet-where-we-live.html.

 References:

 

1 Britannica encyclopedia.

 

2 Spera, Frank J. (2000). "Physical Properties of Magma". In Sigurdsson, Haraldur (ed.). Encyclopedia of Volcanoes. Academic Press. pp. 171–90. ISBN 978-0126431407.

 

3 Schmincke, Hans-Ulrich (2003). Volcanism. Berlin: Springer. pp. 49–50. ISBN 9783540436508.

 

4 Irifune, Tetsuo; Kurio, Ayako; Sakamoto, Shizue; Inoue, Toru; Sumiya, Hitoshi (2003). "Materials: Ultrahard polycrystalline diamond from graphite". Nature. 421 (6923): 599–600. Bibcode:2003Natur.421..599I. doi:10.1038/421599b. PMID 12571587. S2CID 52856300.

 

5 Collins, A. T. (1993). "The Optical and Electronic Properties of Semiconducting Diamond". Philosophical Transactions of the Royal Society A. 342 (1664): 233–244. Bibcode:1993RSPTA.342..233C. doi:10.1098/rsta.1993.0017. S2CID 202574625.

6  Frondel, Clifford; Marvin, Ursula B. (1967). "Lonsdaleite, a new hexagonal polymorph of diamond". Nature. 214 (5088): 587–589. Bibcode:1967Natur.214..587F. doi:10.1038/214587a0. S2CID 4184812.

7 Dienwiebel, Martin; Verhoeven, Gertjan; Pradeep, Namboodiri; Frenken, Joost; Heimberg, Jennifer; Zandbergen, Henny (2004). "Superlubricity of Graphite" (PDF). Physical Review Letters. 92 (12): 126101. Bibcode:2004PhRvL..92l6101D. doi:10.1103/PhysRevLett.92.126101. PMID 15089689. S2CID 26811802. Archived (PDF) from the original on 2011-09-17.

8 ^ Deprez, N.; McLachan, D. S. (1988). "The analysis of the electrical conductivity of graphite conductivity of graphite powders during compaction". Journal of Physics D: Applied Physics. 21 (1): 101–107. Bibcode:1988JPhD...21..101D. doi:10.1088/0022-3727/21/1/015. S2CID 250886376.

 

9 ^ Delhaes, P. (2001). Graphite and Precursors. CRC Press. ISBN 978-90-5699-228-6.

10 Wikipedia