It doesn't conduct electricity because of the lack of ions or mobile electrons. It fumes in moist air because it reacts with water in the air to produce hydrogen chloride. If you add water to silicon tetrachloride, there is a violent reaction to produce silicon dioxide and fumes of hydrogen chloride. In a large excess of water, the hydrogen chloride will, of course, dissolve to give a strongly acidic solution containing hydrochloric acid.
This simple covalent chloride exists as a fuming liquid at room temperature because there are only van der Waals dispersion forces and dipole-dipole attractions between the molecules. The liquid does not conduct electricity because of the lack of ions or mobile electrons. Phosphorus III chloride reacts violently with water to generate phosphorous acid, H 3 PO 3 , and hydrogen chloride fumes or a solution containing hydrochloric acid in excess of water :.
Phosphorus V chloride is structurally more complicated than phosphorus III chloride. Increasing the temperature beyond its sublimation point dissociates divides reversibly more the phosphorus V chloride into phosphorus III chloride and chlorine:. Phosphorus V chloride is an ionic solid.
The formation of the ions involves two molecules of PCl 5. Because only van der Waals dispersion forces exist between these molecules, the species vaporizes. Solid phosphorus V chloride does not conduct electricity.
Phosphorus V chloride reacts violently with water, producing hydrogen chloride fumes. As with the other covalent chlorides, if there is enough water present, these dissolve to give a hydrochloric acid solution.
The reaction happens in two stages. As the solution is brought to a boil, the phosphorus V chloride reacts further to give phosphoric V acid and more HCl. Phosphoric V acid is also known as phosphoric acid or as orthophosphoric acid:. Disulfur dichloride is one of three sulfur chlorides and is the species formed when chlorine reacts with hot sulfur.
Disulfur dichloride is an orange, unpleasant-smelling covalent liquid. Its rather unusual structure is given below:.
Disulfur dichloride reacts slowly with water to produce a complex mixture of hydrochloric acid, sulfur, hydrogen sulfide and various sulfur-containing acids and anions. Jim Clark Chemguide. The structures : Sodium chloride and magnesium chloride are ionic and consist of large ionic lattices at room temperature. Aluminum chloride and phosphorus V chloride are more complicated.
They change their structures from ionic to covalent as their solids transition to liquids or vapors. This is discussed in greater detail below. The other chlorides are simple covalent molecules. Melting and boiling points: Sodium and magnesium chlorides are solids with high melting and boiling points because of the large amount of heat which is needed to break the strong ionic attractions.
The rest are liquids or low melting point solids. Leaving aside the aluminum chloride and phosphorus V chloride cases where the situation is quite complicated, the attractions in the others will be much weaker intermolecular forces such as van der Waals dispersion forces.
These vary depending on the size and shape of the molecule, but will always be far weaker than ionic bonds. Electrical conductivity: Sodium and magnesium chlorides are ionic and so will undergo electrolysis when they are molten. Electricity is carried by the movement of the ions and their discharge at the electrodes not electrons. In the aluminum chloride and phosphorus V chloride cases, the solid does not conduct electricity because the ions aren't free to move.
In the liquid where it exists - both of these sublime at ordinary pressures , they have converted into a covalent form, and so don't conduct either. The rest of the chlorides do not conduct electricity either solid or molten because they don't have any ions or any mobile electrons. Reactions with water : As an approximation, the simple ionic chlorides sodium and magnesium chloride just dissolve in water. Although other chlorides all react with water in a variety of ways described below for each individual chloride.
The reaction with water is known as hydrolysis. Sodium chloride NaCl Sodium chloride is an ionic compound consisting of a giant array of sodium and chloride ions. A small representative portion of a sodium chloride lattice looks like this: This is normally drawn in an exploded form as: The strong attractions between the positive and negative ions require a large amount of heat energy to break, so sodium chloride has high melting and boiling points.
Magnesium chloride MgCl 2 Like sodium chloride, magnesium chloride also forms an ionic solid, but with a more complicated crystal structure of the ions to accommodate twice as many chloride ions as magnesium ions. Aluminum chloride AlCl 3 Electronegativity increases across the period; aluminum and chlorine do not differ enough in electronegativity to form a simple ionic bond. The structure is shown below: In the conversion, all ionic character is lost, causing the aluminum chloride to vaporize or melt depending on the pressure.
This causes it to melt or vaporize due to comparatively weak intermolecular attractions. As the temperature increases further, more AlCl 3 molecules are formed. Silicon tetrachloride SiCl 4 Silicon tetrachloride is a simple no-messing-about covalent chloride.
Phosphorus III chloride PCl 3 This simple covalent chloride exists as a fuming liquid at room temperature because there are only van der Waals dispersion forces and dipole-dipole attractions between the molecules. Disulfur Dichloride S 2 Cl 2 Disulfur dichloride is one of three sulfur chlorides and is the species formed when chlorine reacts with hot sulfur. Its rather unusual structure is given below: The molecule's conformation indicates its possible intermolecular interactions: There is no plane of symmetry in the molecule; therefore, it has an overall permanent dipole.
In liquid state, the molecule experiences van der Waals dispersion forces and dipole-dipole attractions. There are no ions in disulfur dichloride and no mobile electrons, making it nonconductive.
The ions cannot move to conduct the electric current. But when an ionic compound melts, the charged ions are free to move. Therefore, molten ionic compounds do conduct electricity. When a crystal of an ionic compound dissolves in water, the ions separate.
Again, the ions are free to move - so a solution of an ionic compound in water also conducts electricity. Ionic bonding The ions in a compound such as sodium chloride are arranged in a lattice structure.
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