Who is the melting point of graphite and diamond?
When diamond and graphite melt, the covalent bonds of C-C must be destroyed. With the C-C bond, the longer the bond length, the lower the bond energy (the length of the stick is easily broken). Therefore, the diamond bond length is larger than graphite, and the melting point is less than graphite.
Graphite is a thermodynamically stable structure, while diamond is thermodynamically unstable. Diamond is an atomic crystal, a spatial network structure. Each layer of graphite is netted, and between layers is the intermolecular force, which is the crystal structure between the molecular crystal and the atomic crystal. But because of the bond length, the covalent bond length in the layer of graphite is longer than the bond length of the diamond, and the intermolecular force is greater. The destruction of the chemical bond requires more energy. Agree with this statement. Added, diamond heated to 1900 degrees Celsius will be converted to graphite, graphite more stable.
When material melts, molecular crystals need to destroy intermolecular forces; atomic crystals need to destroy covalent bonds; ionic crystals need to destroy ionic bonds; metal crystals need to destroy metal bonds. The stronger the bond, the higher the energy required for the breaking key, the higher the melting point.
