Brownian Movement

The term Brownian movement stands for the random zig-zag motion of a particle when it’s observed under a high-power ultra-microscope. It’s named after the Scottish Botanist Robert Brown, who explained the resemblance of this movement with pollen grains in water; hence it’s known as the Brownian movement. Later on, Albert Einstein wrote a paper on the Brownian movement explaining it more clearly. This discovery of the random motion of particles initiated the early thought process of the existence of atoms and molecules. Hence, it’s crucial to understand the Brownian Movement thoroughly as it covers the basics of modern atomic theory.

Define Brownian Movement 

Brownian movement or Brownian motion is the random fluctuations of particles in a fluid as they constantly collide with other fast-moving molecules. It’s an uncontrolled motion of particles at the microscopic level that resembles the impact of molecules of the surrounding medium.

After the collision, a particle changes its path and follows a random zig-zag motion. This process involves an exchange of energy and momentum between particles. This is used to identify colloidal solutions.

Brownian movement in colloids 

Generally, the Brownian movement can be observed in all types of colloids. It proves that the particles of colloid solution are not steady and in motion always—such random motion results from heterogeneous solution and non-uniform bombardments between particles with dispersed phases. Brownian movement causes a constant stirring effect which does not allow the particles of the colloidal solution to settle. It is thus a stabilising element too.

On the contrary, the Brownian movement cannot be observed in true solutions. The reason is its homogeneous nature and static particles. 

Brownian Movement Examples

Brownian Movement can be easily observed in everyday phenomena, including motion and transport processes.

Examples of the Brownian Movement include: 

• Pollen grains under a microscope with water, as observed by Robert Brown

• Diffusion of Calcium through bone tissues in living organisms

• Diffusion of dust pollutants through the atmosphere

• Plasma particles present in the cells cause transfer of energy and change in momentum. This transfer causes the Brownian movement

• The haphazard motion of electrons in a conductor

• Diffusion of perfume through air

Causes of Brownian Movement

Brownian movement occurs when the dispersed phase molecules are impacted highly by the dispersion medium. Since the molecules collide with other particles, it creates an unequal impact on the colloidal particles, which results in a zig-zag motion. It creates momentum and energy exchange between colliding molecules. 

Additionally, factors such as particle’s size, the momentum of transfer of molecules, speed of collisions, viscosity of fluid, etc., highly affect the Brownian movement.

To conclude, the unbalanced bombardment of the colloidal particle by the molecules of dispersion medium causes Brownian movement.

Factors Affecting Brownian Motion:

• It is inversely proportional to size of the molecule: The bigger the size, the smaller will be the velocity as energy is fixed at a given temperature.

• It is inversely proportional to the viscosity of the medium: Higher the viscosity of the medium, it will offer more resistance to brownian motion and vice-versa

• It is directly proportional to the temperature: As temperature increases, the energy of the molecules increases leading to more velocity of the particles in brownian motion.

Importance of Brownian Movement 

The importance and contribution of the Brownian movement can be summarised as follows: 

• One of the foremost importance of the Brownian Movement in chemistry is that it laid the foundation for the modern atomic theory. 

• It also formed a base for the mathematical models used in mathematics, physics, economics, biology, engineering, and chemistry.

• Also, it causes the particles of a solution to be in constant motion; hence, it prevents particles from settling down, which provides stability to colloidal solutions.

• Apart from this, the basics of the kinetic theory of gases can be traced down to the Brownian movement.

• This theory has a significant contribution to the discovery and existence of molecules and atoms.

Conclusion 

The Brownian movement can be regarded as a visible particle picture after being influenced by random microscopic effects. From a subtle observation of pollen grains moving randomly in water, Robert Brown generated an understanding of the Brownian movement that was officially adopted and published with a proper study by Albert Einstein. From being a chemistry study to contributing to complex mathematical models and forming a base for modern atomic theory, the Brownian movement has served as a great discovery.