The force of attraction between particles in a liquid is called intermolecular forces. These forces are weaker than the forces that hold atoms together within a molecule (intramolecular forces), but they are still strong enough to keep the liquid molecules close together.

There are several types of intermolecular forces, including:

* Hydrogen bonding: This is the strongest type of intermolecular force and occurs when a hydrogen atom is bonded to a highly electronegative atom like oxygen, nitrogen, or fluorine. This creates a strong dipole-dipole interaction.

* Dipole-dipole interactions: These occur between polar molecules, where one end of the molecule has a partial positive charge and the other end has a partial negative charge. These partial charges attract each other.

* London dispersion forces: These are the weakest type of intermolecular force and occur between all molecules, even non-polar ones. They arise from temporary fluctuations in electron distribution around the molecules.

* Ion-dipole interactions: These occur between an ion and a polar molecule. The ion will be attracted to the oppositely charged end of the polar molecule.

The strength of these forces determines many of the properties of liquids, such as their boiling point, viscosity, and surface tension.

Here's a simple way to think about it:

* Stronger intermolecular forces: Lead to higher boiling points, higher viscosity, and higher surface tension. This is because the molecules are more strongly attracted to each other and need more energy to overcome these forces.

* Weaker intermolecular forces: Lead to lower boiling points, lower viscosity, and lower surface tension. The molecules are more easily separated.

Let me know if you would like to know more about specific intermolecular forces!