The Macroscopic Scale

The macroscopic scale involves the substances that are large enough to be visible to the human eye (without the help of optical instruments to provide a magnified view).  Some important quantities that are dealt with on the macroscopic scale include:

• Melting and boiling points
• The coefficient of linear thermal expansion
• Latent heat of vaporization
• Enthalpy of fusion

Considering the example of a water molecule, the macroscopic scale involves its physical state (solid, liquid, or gaseous) but does not deal with the chemistry of the H₂O molecule.

The Microscopic Scale

The microscopic scale deals the with properties of substances that can only be seen by the human eye with the help of optical instruments that magnify the substance, such as microscopes.

The study of the shapes and structures of crystals fall under this scale. The structures of crystals have an impact on the behaviour of large sections of the crystals, which are used in bridges and aeroplanes.

The Atomic Scale

• The properties of matter at the atomic scale vary from element to element.
• However, some elements exhibit similar properties and are grouped together in the periodic table.
• Some examples of the properties of matter studied in physical chemistry at the atomic scale include atomic mass and atomic number.
• The value of the atomic radii of elements can be used to determine the bond length of the bond between two atoms in a molecule.

Subatomic Scale

• The subatomic scale involves the study of particles that are smaller than the size of atoms, generally referred to as subatomic particles.
• At this scale, the dual nature of particles is the reason that subatomic particles are sometimes referred to as waves or energy.
• The study of physical chemistry at a very advanced level involves the study of subatomic particles.
• The study of these particles also have applications in the field of nuclear chemistry.

As the name suggests, physical chemistry uses the techniques, theories, and principles that are associated with physics to explain certain aspects of chemistry. It can be noted that factors such as temperature and pressure have an impact at the macroscopic and the microscopic level but their impact diminishes at the atomic and the subatomic scales.