Activity 1: Atoms are held together in molecules by strong intramolecular forces, like covalent and ionic bonds. On the other hand, other forms of attractive forces are present to keep these molecules together giving rise to the different states of matter, which, then exhibit their own bulk properties such as boiling, melting, and freezing points, and viscosity among others. There are three general types of intermolecular forces (IMF), namely, van der Waals forces, ion-dipole interaction, and H-bonding. Van der Waals forces, after the Dutch chemist Johannes van der Waals (1837-1923) consist of dipole-dipole interaction, dipole-induced dipole interaction, and dispersion forces. Dipole-dipole attraction is present among polar molecules. Through constant movement, the charges of the molecules align in such a way that the positive (+) end of one molecule is attracted to the negative (-) end of the other molecule. This happens due to the shift of electron density towards the more electronegative element in the molecule resulting to (+) and (-) ends. The measure of this electron shift is known as dipole moment, represented by crossed arrow,+. Dipole-induced dipole interaction, just like the dipole-dipole forces, depends on the presence of polar molecules. The other molecule needs not be a polar one. The partial charges present in the dipole cause the polarization or distortion of the electron distribution of the other molecule. This gives rise to regions of partial (+) and (-) poles. This induced dipole will then be attracted to the original polar molecules, resulting to dipole-induced dipole attraction. Dispersion forces (London dispersion forces), were named after the German physicist Fritz London (1900-1954). The electron cloud of a neutral substance can be normally distributed around the nucleus. At any given time, the electron distribution may be uneven resulting to an instantaneous dipole. This temporary dipole will then influence the neighbouring atoms through attractive and repulsive forces. Eventually, the substances will gain instantaneous dipoles, too. Attraction between opposite charges will happen among the species present. These are true for ion-induced dipole and induced dipole-induced dipole interactions. Ion-dipole interaction results from the attraction between either a cation (+) or an anion (-) with permanent polar molecules. The ions will be attracted to the opposite charges present in the dipole resulting to this type of attraction.​