2.4 Period 3

• The properties of period 3 elements and their oxides are discussed in this video for AQA.
• Sodium, which is in Group 1, is more reactive than magnesium, which is in Group 2, when they lose electrons.
• Sodium forms an Na+ ion when it loses electrons, while magnesium forms an Mg2+ ion.
• Phosphorus pentoxide (P4O10) and sulfur dioxide (SO2) form simple molecular structures and their melting points are lower due to the weak intermolecular forces holding them together.
• Aluminium oxide has a slightly lower melting point than magnesium oxide due to the distortion of the electron cloud by aluminium ions.
• The melting points of Group III oxides vary, with sodium oxide having a lower melting point than magnesium oxide due to the larger charge on the magnesium ions.
• Silicon dioxide has a higher melting point than the rest of the non-metal oxides due to its macro molecular structure.
• Sodium reacts vigorously with cold water and forms a ball and starts fizzing because it's producing hydrogen gas.
• The hydrogen gas produced by sodium can be tested by using a lighted splint, which produces a squeaky pop.
• Sodium reacts with water to form sodium hydroxide and water.
• Sulfurous acid, or SO3, reacts with water to form H2SO3, a sulfuric acid.
• Sodium oxide reacts with water to form sodium hydroxide, which is an alkaline alkaline solution.
• Sodium hydroxide is a strong base that readily dissolves in solution and has a high pH.
• Magnesium hydroxide does not dissolve very well in water and its pH is lower than that of sodium hydroxide.
• Sulfuric acid, or H2SO4, is made using sulfur trioxide and sulfur dioxides.
• Phosphorus pentoxide, or P4O10, reacts with water to form phosphoric acid, which breaks down into three H+ ions and PO4- ions.
• Ionic oxides form basic solutions, while simple covalent oxides form acidic solutions.
• Magnesium does react with water, but it reacts incredibly slowly and forms a weak alkaline solution of magnesium hydroxide.
• Magnesium's weak alkaline solution is sparingly soluble, which is why it doesn't have many OH- ions.
• Silicon reacts with oxygen to form silicon dioxide, SiO2.
• Sulfur dioxide burns steadily in oxygen.
• Aluminium reacts with oxygen to form aluminium oxide, Al2O3.
• Magnesium reacts much faster with steam than with water, producing an oxide instead of a hydroxide.
• Phosphorus spontaneously combusts when a small amount of heat is applied.
• Magnesium reacts with water to form magnesium hydroxide and hydrogen.
• Sulfur forms sulfur dioxide, which has an oxidation number of +4 at a higher temperature and catalyst.
• Magnesium reacts with oxygen to form magnesium oxide.
• Magnesium oxide reacts with air to form magnesium oxide and heat.
• Aluminium oxide is slow to react with air, but it reacts faster if it's powdered.
• The structure and bonding of Group three oxides affects their melting points.
• Phosphorus reacts with oxygen to form P4.
• Sodium oxide reacts with air to form sodium oxide and heat.
• Sodium reacts with half oxygen to form two lots of sodium oxide.
• The equilibrium lies well to the left in the case of magnesium, as it doesn't dissociate very well when it's dissolved in water.
• Sodium oxide, another metal oxide, will react with an acid such as sulfuric acid to form sodium sulfate and water.
• Silicon dioxide forms giant covalent structures and requires loads of energy to break these, making it insoluble in water and reacting with a base to form a salt.
• Silicon dioxide is classified as an acid because it reacts with a base to form a salt.
• Silicon dioxide reacts with acids to produce salt water.
• Aluminium oxide is amphoteric, behaving both as an acid and a base.
• Aluminium oxide is insoluble in water and does not dissolve readily due to some of its covalent character.