Properties of Liquids

Study Notes

Liquids have a definite volume but no definite shape.
Liquids take the shape of their container.
Liquids are relatively incompressible.
Adhesion: Attraction between different molecules. An example is tape sticking to paper.
Cohesion: Attraction between like molecules. An example is Mercury forming beads.
Surface Tension: A phenomenon where liquid molecules resist an external force due to cohesive forces.
Viscosity: A measure of a fluid's resistance to flow. High viscosity means strong intermolecular forces (IMF), while low viscosity implies weaker IMFs. An example of high viscosity is honey, and water has low viscosity.
Capillarity: The ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. This is caused by interactions between the liquid molecules and the surface of the container (adhesion forces) being stronger than the cohesive forces between the liquid molecules themselves.
- Capillary rise depends on the narrowness of the tube.
Vapor Pressure: The pressure exerted by a gas/vapor in equilibrium with its liquid or solid phase in a closed system at a given temperature.
Boiling Point: The temperature at which the vapor pressure of a liquid equals the surrounding atmospheric pressure. Different substances have different boiling points.
Molar Heat of Vaporization: The energy needed to transform a given amount of liquid into gas at a set pressure.

Water molecules are polar, with a slightly negative oxygen end (δ-) and two slightly positive hydrogen ends (δ+).
Hydrogen bonding occurs between the δ- end of one water molecule and the δ+ ends of other water molecules. This explains many unique properties of water.

Crystalline solids: Possess highly ordered atomic arrangements forming well-defined structures.
Amorphous solids: Lack long-range order in their atomic or molecular arrangement. The arrangement is random and disordered.

Ionic solids: Composed of positively and negatively charged ions held together by strong electrostatic forces (ionic bonds). Examples include NaCl (sodium chloride) and MgO (magnesium oxide).
Metallic solids: Composed of metal atoms arranged in regular lattice structures held together by metallic bonds (delocalized electrons). Examples include Au (gold) and Al (aluminum).
Covalent solids: Atoms are covalently bonded in a continuous network structure. These solids are extremely hard and have very high melting points. Examples include diamond.
Molecular solids: Consist of covalently bonded molecules attracted to each other by weak intermolecular forces (Van der Waals forces). Examples include carbon dioxide (CO2) and iodine (I2).