There is a correlation between the electronegativity of the metal in the chloride and the acidity of the solution formed upon hydrolysis, although it's not as direct or straightforward as other factors like ionic charge and atomic radius. Electronegativity, which measures an atom's ability to attract and hold onto electrons, does play a role in determining how a metal ion will interact with water during hydrolysis. Generally, metals with higher electronegativity tend to form chlorides that hydrolyse to produce more acidic solutions. This is because a more electronegative metal ion will more strongly attract the electron density of water molecules, facilitating the release of H⁺ ions and thus leading to an acidic solution. However, it's important to consider that electronegativity is just one of several factors affecting hydrolysis and resulting pH. The oxidation state and size of the metal ion (which are related to its polarising power) are often more directly correlated with the nature of hydrolysis and the acidity of the solution. In the context of Period 3 elements, as we move from left to right across the period, there is an increase in electronegativity, which coincides with an increase in the acidity of the hydrolysis products, but this trend is more strongly influenced by the increasing oxidation state and decreasing ionic radius.

Temperature plays a significant role in the hydrolysis of chlorides and consequently affects the pH of the resultant solution. Generally, increasing the temperature accelerates the hydrolysis reactions. This is because higher temperatures provide more kinetic energy to the reacting molecules, increasing the frequency and energy of collisions, which in turn increases the rate of reaction. For instance, the hydrolysis of silicon tetrachloride (SiCl₄) is more rapid and complete at higher temperatures, leading to more hydrochloric acid being formed, and thus a lower pH. Additionally, for reactions that are endothermic (absorb heat), an increase in temperature can shift the equilibrium position towards the right, leading to more products, including H⁺ ions, being formed. However, it's important to note that the extent of the temperature effect can vary depending on the specific chloride and the details of the hydrolysis reaction. Furthermore, in some cases, especially where the hydrolysis reaction is exothermic (releases heat), increasing temperature might slightly decrease the extent of reaction, though this is less common in the hydrolysis of simple chlorides.

The pH of the solution formed by the hydrolysis of chlorides can provide insights into the nature of the oxide formed by the same metal. Generally, metals forming acidic solutions upon chloride hydrolysis tend to form acidic or amphoteric oxides, while those forming neutral solutions upon hydrolysis tend to form basic oxides. For instance, aluminium chloride (AlCl₃) hydrolyses to form an acidic solution, indicating that aluminium oxide (Al₂O₃) is likely to be amphoteric, having both acidic and basic properties. Similarly, sodium chloride (NaCl) forms a neutral solution upon hydrolysis, which aligns with sodium oxide (Na₂O) being a basic oxide. This relationship is grounded in the chemical behaviour of the metal cations and their interaction with oxygen and water. Metals with higher charge density, which form acidic solutions upon chloride hydrolysis, have a strong polarising effect on the oxide ion, leading to the formation of covalent character in their oxides, which in turn exhibits acidic or amphoteric properties. In contrast, metals that form neutral solutions have lower charge densities and form ionic bonds with oxide ions, resulting in basic oxides.

The hydrolysis of sodium chloride (NaCl) leads to a neutral solution due to the nature of its constituent ions, Na⁺ and Cl⁻. Sodium ion, being a cation from a strong base (NaOH), and chloride ion, an anion from a strong acid (HCl), do not react significantly with water. The lack of further reaction means that no additional H⁺ or OH⁻ ions are introduced into the solution, thus maintaining a neutral pH. In contrast, other Period 3 chlorides involve cations from weaker bases and/or anions that hydrolyse to form acids. For instance, in the case of magnesium chloride (MgCl₂), the Mg²⁺ ion reacts with water, slightly increasing the concentration of H⁺ ions, while the Cl⁻ ion contributes to the formation of hydrochloric acid. These reactions lead to an increase in H⁺ ion concentration, resulting in an acidic solution. The difference in the chemical behaviour of Na⁺ compared to other Period 3 cations, like Mg²⁺, Al³⁺, Si⁴⁺, and P⁵⁺, explains why NaCl hydrolysis yields a neutral solution, whereas others result in acidic solutions.

The hydrolysis of Period 3 chlorides provides a clear reflection of the periodic trends in chemical properties across the period. One of the most notable trends observed is the change in the nature of the hydrolysis products from neutral to increasingly acidic as we move from left to right across the period. This trend is closely associated with the increasing electronegativity, decreasing atomic radius, and increasing oxidation states of the elements. As these changes occur, the cations formed from these elements (e.g., Na⁺, Mg²⁺, Al³⁺, Si⁴⁺, P⁵⁺) have increasing polarising power, which influences their interaction with water during hydrolysis. The increased polarising power leads to stronger attraction to the electron density of water, facilitating the release of more H⁺ ions and thus forming more acidic solutions. Additionally, the nature of bonding in the chlorides changes across the period, from ionic in the case of sodium chloride to more covalent in phosphorus pentachloride, which also influences the hydrolysis reactions and the acidity of the resultant solutions. This trend exemplifies the general periodic trend of increasing non-metallic character and decreasing metallic character across a period.