# Cohesion (chemistry)

Water pearl in equilibrium between cohesion and gravity

In physics and chemistry, cohesion (from Latin cohaesum , participle of: cohaerere “to be connected”) is the term used to describe the bonding forces between atoms and between molecules within a substance . The forces ensure his cohesion. They act in liquids or solids and lead to the surfaces of a substance to surface tension . On the other hand, adhesion is based on binding forces between two different phases .

## Cohesive energy

The simplest type of plastic deformation is to remove a particle. The energy that is necessary to remove a particle from an infinitely extended ideal crystal is the cohesive energy:

${\ displaystyle E _ {\ text {coh}}: = \ sum _ {i = 1; i \ neq j} ^ {N} {\ frac {1} {N}} \ Phi _ {ij} (r_ {ij })}$

Here is the number of particles in the system and the interaction energy between two particles and grossly neglecting the multibody terms. ${\ displaystyle N}$${\ displaystyle \ Phi _ {ij} (r_ {ij})}$${\ displaystyle i}$${\ displaystyle j}$

## causes

The cohesion is caused by the following interactions: