The following are the differences in the properties of diamond and graphite based on their structures are -
1. Diamond is vary hard whereas graphite is soft:
In diamond there is a three dimensional network of strong covalent bonds. This makes diamond extremely hard. Because of hardness, diamond is used in making cutting and grinding tools.
On the other hand, in graphite there are flat layers of carbon atoms. These layers are held by weak van der Waal’s forces and hence can easily slip one over the other. This makes graphite extremely soft and slippery. Because if this soft and slippery nature graphite is used as a lubricant.
2. Density of diamond is more than that of graphite: In graphite, there are large spaces between adjacent layers due to weak forces between them.
On the other hand, in diamond, atoms are held by strong covalent bonds and relatively more closely packed. Hence, diamond has higher density than graphite. Density of diamond is 3510 kg/m3 whereas that of graphite is 2250 kg/m3.
3. Diamond is bad conductor of electricity whereas graphite is a good conductor
In diamond, each carbon atom is directly linked to four other carbon atoms through covalent bonds. Thus, in diamond all the four valence electrons carbon are involved in covalent bonds and are not free to conduct electricity. This makes diamond a bad conductor of electricity.
On the other hand, in graphite each carbon atom is directly bonded to only three other carbon atoms. Thus, each carbon atoms utilizes only three valence electrons for forming covalent bonds with other carbon atoms, the fourth valence electron is relatively free, can move from one carbon atom to the other in a layer, and hence is responsible for conducting electricity. Hence, graphite is a good conductor of electricity.
4. Melting points of graphite and diamond are very high:
In diamond as well as in graphite carbon atoms are held by strong net work of covalent bonds. Therefore, both have very high melting points. The melting point of graphite is slightly higher than the melting point of diamond because in graphite C-C bonds have partial double bond character and hence are stronger and difficult to break. In factor, carbon as graphite has the highest melting point among all the elements.
