Question

Diamond is hard because

• A. all the four valence electrons are bonded to each carbon atoms by covalent bonds
• B. it is a giant molecule
• C. it is made up of carbon atoms
• D. it cannot be burnt

Hint:

Diamond is one of the allotropic forms of carbon. 

Answer 1

The Correct Option is A

Diamond is hard because all the four valence electrons are bonded to each carbon atom by covalent bonds. 

Diamond has all the carbon atoms sp³ hybridized. These are linked to four other carbon atoms tetrahedrally by covalent bonds. The covalent bonds hold the atoms firmly making it the hardest substance on earth. 

Some of the characteristic properties of the diamond structure are:

• Each carbon atom is present at the centre of a regular tetrahedron. 
• Each carbon atom is surrounded by four other carbon atoms present at the corners of a regular tetrahedron. 
• The octet of each carbon atom is complete. 
• The structure of a diamond is a rigid three-dimensional network giving it the hardness property. 
• Diamond is chemically inactive due to its rigid three-dimensional structure. 
• Very high energy is required to break the large number of covalent bonds present in diamond and that is why diamond has a very high melting point. 

Also Read: Chemical Bonding & Molecular Structure