periodicity

• Period 3 Oxides & Hydroxides: Acid/Base Behaviour
• Period 3 Chlorides
• Period 3 Elements: Electronegativity & Bonding
• Element X forms an oxide with a melting point of 1610 °C, suggesting a giant molecular (covalent) structure which corresponds to Group 14.
• Reaction with oxygen: reacts with oxygen to form an oxide of SeO (if compared with sulfur).
• Group 15 chlorides get hydrolysed in water, indicating this is a hydrolysis reaction.
• Chemical properties of simple molecules are: Reaction with water: simple molecules do not react with water.
• Physical properties of simple molecular structures are low melting points, do not conduct electricity and are insoluble in water.
• Selenium is a nonmetal in Group 16 and if compared to sulfur, its structure is predicted to be a simple molecular structure.
• Group 1 and 2 chlorides react with water to form colourless solutions of pH 6.5 − 7.
• Group 15 chlorides react with water to form strong acidic solutions.
• Reaction with chlorine: reacts with chlorine to form simple molecule of SeCl which can react with the water vapour in air to form hydrogen chloride (if compared with sulfur).
• Element X forms a chloride which reacts with water to form a solution of pH 1, suggesting it is a non-metallic chloride (group 13 to 17).