Cohesion (chemistry) facts for kids
It is a property of a substance that is caused by the shape and structure of its molecules, which makes the distribution of electrons irregular when molecules get close to one another, creating electrical attraction that can maintain a microscopic structure such as a water drop.
In other words, cohesion allows for surface tension, creating a "solid-like" state upon which light-weight or low-density materials can be placed.
Water, for example, is strongly cohesive as each molecule may make four hydrogen bonds to other water molecules in a tetrahedral configuration. This results in a relatively strong Coulomb force between molecules.
Cohesion (chemistry) Facts for Kids. Kiddle Encyclopedia.