There are two main forces of attraction in liquids. The first is the London dispersion force, which occurs when there is an unequal distribution of elections in an atom so that each atom has two opposite and equal poles called dipoles. This affect is temporary

The second force of attraction is Dipole-dipole. In order to understand what a dipole-dipole force is, we first need to understand what a polar molecule is. A polar molecule is when a molecule has a slightly positive charged side and a slightly negative charged side, like a very tiny magnet. A dipole-dipole forces occurs when the positive side of a molecule attracts the negative side of another molecule, behaving much like two magnets.

Difference between elements and compounds:
Elements are made of one type of molecule, while compounds are made of at least two different elements and can be separate by chemical means into those different elements.
Difference between homogeneous mixtures and heterogeneous mixtures:
A homogeneous mixture has a uniform appearance and composition throughout the mixture. A heterogeneous mixture is made of a bunch of visibly different substances and/or the substance is may be more than one state of matter.
Difference between pure substances and mixtures:
 A mixture can be physically separated into pure substances or elements. Pure substances are made of a uniform composition of elements and compounds. A mixture may have various boiling point, while a a pure substance has only one boiling point.