There are three main types of solids: amorphous solids which have an irregular atomic structure and are isotropic, polycrystalline solids which are aggregates of many small crystals joined at grain boundaries, and single crystals which consist of a single crystal with no grain boundaries.

1. ***Write the general types of solids
There are three general types of solids. They are:
1.Amorphous
2.Polycrystalline
3.Single crystal

3. Amorphous
1.They do not have a regular arrangement of
atoms, molecules or ions.
2.They are known as pseudo solids.
3.They are isotropic, i.e, they have same directions
for different physical properties.
4.Examples are rubber, glass, etc.

4. 2.Polycrystalline
Polycrystalline material – Aggregate of several crystals
or grains .
The boundary between the grain is the grain
boundary across which the orientation of the crystal
changes.
The point at which three boundaries meet is called
the triple junction. Triple junction

5. 3.Single crystal
Single crystal – only one grain or crystal and hence,
no grain boundaries.
Useful for applications where grain boundaries are
harmful.