Difference Between Diamond and Graphite

Main Difference – Diamond vs Graphite

Diamonds and graphite are known as allotropes of carbon since these substances are made out of only carbon atoms, and the arrangement of these carbon atoms are different from each other. Although they are composed of carbon atoms, diamond and graphite have different chemical and physical properties that arise according to the differences in their structures. Although there are many differences between these two substances, the main difference between diamond and graphite is that diamond is made out of sp³ hybridized carbon atoms whereas graphite is made out of sp² hybridized carbon atoms.

Key Areas Covered

1. What is Diamond
      – Definition, Properties, and Uses
2. What is Graphite
      – Definition, Properties, and Uses
3. What is the Difference Between Diamond and Graphite
      – Comparison of Key Differences

Key Terms: Allotropes, Carbon, Diamond, Graphite, Hybridization

What is Diamond

Diamond is a very stable allotrope of carbon that is composed of sp³ hybridized carbon atoms. The arrangement of these carbon atoms in diamond is called the face-centered cubic crystal structure. Here, each and every carbon atom is bonded to four other carbon atoms and these carbon atoms are also bonded to four other carbon atoms.  Likewise, a network structure is created, making the diamond a hard and stable substance.

Figure 1: Diamond

The appearance of diamond is colorless and shiny. All chemical bonds between carbon atoms are covalent bonds. There, the sp³ hybridized carbon atoms are bonded to each other. A specific feature of diamond is its high dispersion of light. Diamond is a transparent substance. Both hardness and dispersion of light make diamond to be used in industrial applications and jewelry production. Diamond is the hardest mineral substance that has been found on the earth. Diamond is extremely hard and transparent. It doesn’t conduct electricity and has a higher melting point.

What is Graphite

Graphite is an allotrope of carbon that is made out of sp² hybridized carbon atoms. It is a good electrical conducting material. One carbon atom is bonded to three other carbon atoms. These carbon atoms are also bonded to three other atoms, forming a network structure. The crystal structure of graphite is planar. The color of graphite is greyish black. It is an opaque substance. Graphite is not hard. It feels soft and slippery to touch.

Since the carbon atoms of graphite are sp2 hybridized atoms, there are non-hybridized p orbitals in carbon atoms. Each and every carbon atom is composed of one non-hybridized p orbital per one carbon atom. Therefore, these free p orbitals can be mixed with each other forming an electron cloud. The electron cloud is created parallel to the planar structure of graphite. This electron cloud causes the electrical conducting of graphite.

Figure 2: Graphite

Graphite has many industrial applications. Graphite powder is used as a dry lubricant. Graphite solid substance is used as an electrode. For example, graphite electrode is the anode of the Lithium ion batteries. Graphite is a common refractory material because it withstands high temperatures without changing chemically. Graphite is used in pencils.

Difference Between Diamond and Graphite

Definition

Diamond: Diamond is a very stable allotrope of carbon that is composed of sp³ hybridized carbon atoms.

Graphite: Graphite is an allotrope of carbon that is made out of sp² hybridized carbon atoms.

Hardness

Diamond: Diamond is the hardest mineral found on earth.

Graphite: Graphite is a soft mineral.

Number of Bonds around a Carbon Atom

Diamond: Diamond has four covalent bonds around one carbon atom.

Graphite: Graphite has three covalent bonds around one carbon atom.

Crystal Structure

Diamond: Diamond has a face-centered cubic crystal structure.

Graphite: Graphite has a planar structure.

Transparency

Diamond: Diamond is transparent.

Graphite: Graphite is opaque.

Conclusion

Diamond and graphite are allotropes of carbon. These have different chemical and physical properties. The main difference between diamond and graphite is that diamond is made out of sp³ hybridized carbon atoms whereas graphite is made out of sp² hybridized carbon atoms.

References:

1. Boundless. “Carbon.” Carbon | Boundless Chemistry, Available here. Accessed 22 Sept. 2017.
2. “Diamond.” Wikipedia, Wikimedia Foundation, 22 Sept. 2017, Available here. Accessed 22 Sept. 2017.
3. “GCSE Bitesize: Graphite.” BBC, BBC, Available here. Accessed 22 Sept. 2017.

Image Courtesy:

1. “Cracked Diamond” (Public Domain) via PublicDomainPictures.net
2. “Graphite-233436” By Rob Lavinsky, iRocks.com – (CC BY-SA 3.0) via Commons Wikimedia