Question

The lattice of a covalent crystal is composed of:
a.) Atoms
b.) Molecules
c.) Ions
d.) Compounds

Answer 1

Hint: A solid network or covalent network solid or a covalent network solid is a chemical compound (or element) in which the atoms are covalently bonded in a continuous network extending throughout the substance. So, atoms are the building block of a covalent crystal lattice.

Complete step by step answer:
When we are talking about covalent crystal lattice we are talking about a covalent network solid.
A solid network or covalent network solid or a covalent network solid is a chemical compound (or element) in which the atoms are covalently bonded in a continuous network extending throughout the substance. Here are no individual molecules in a network solid, and the whole crystal or amorphous solid can be called a macromolecule.
Diamonds with a continuous network of carbon atoms and silicon dioxide or quartz with a continuous three-dimensional network of units are examples of network solids. The term glass is used for disordered network solids, they are formed when the liquid form is rapidly cooled which does not allow the atomic ordering to occur properly.

Some properties of the covalent crystal lattice are:
The substances with covalent crystal lattice are usually very hard and hence brittle.
The melting point of these substances is also very high as melting requires the breakdown of the covalent bonds in the lattice.

Depending on the type of the bonding, variable: network solids in which all electrons (e.g. diamond, quartz) are used for sigma bonds are weak conductors since there are no delocalized electrons. Network solids may however, exhibit metal-like conductivity with delocalized pi bonds (e.g. graphite) or dopants.
Hence, as we discussed above the lattice of covalent compounds is made up of atoms.
So, the correct answer is “Option A”.

Note: There also exists a different kind of crystal lattice called the ionic crystal lattice (named so because they are made up of ions). So we see ionic crystal lattice and covalent crystal lattice in our daily life and one simple method of distinguishing them is to try to dissolve them. Covalent lattices usually do not dissolve in any solvent whereas ionic lattices do.