Chemistry Period 3 Metals and Oxides

Period 3 Metals

• Sodium and magnesium react ionically to form positive ions.
• Sodium forms 1+ ions, magnesium forms 2+ ions.
• Sodium is more reactive than magnesium because it only needs to lose one electron, while magnesium needs to lose two electrons.
• This means that sodium requires less energy to ionize, making it more reactive.
• Magnesium reacts slowly with water but reacts violently with steam.
• This is because steam provides more energy, resulting in a bright white flame, hydrogen, and magnesium oxide.

Period 3 Oxides

• Period 3 elements react with oxygen to form oxides with each element in its highest oxidation state.
• This number is often the same as the group number.
• Sodium oxide (Na2O), Magnesium oxide (MgO), Aluminium oxide (Al2O3), Silicon dioxide (SiO2), Phosphorus pentoxide (P4O10), Sulphur dioxide (SO2) are all examples of period 3 oxides.
• The reactivity of each oxide is determined by its structure and bonding:
  • Ionic oxides are generally more reactive.
  • Simple covalent oxides are also reactive.
  • Macromolecular oxides are less reactive.

Oxide Properties

• Oxide structures affect their reactivity and melting points.
• Sodium oxide (Na2O) and Magnesium oxide (MgO) are ionic with high melting points and are highly reactive.
• Aluminium oxide (Al2O3) is ionic with covalent character, has a high melting point and is less reactive.
• Silicon dioxide (SiO2) is a giant covalent structure, highly stable with a high melting point.
• Phosphorus pentoxide (P4O10) is a simple covalent structure, reactive, with a low melting point.
• Sulphur dioxide (SO2) is a simple covalent structure with a low melting point and readily burns.

Reactions with Water

• Ionic oxides (Na2O, MgO) react with water to form alkaline solutions (pH 10-14).
• Simple covalent oxides (SO2, P4O10) react with water to form acidic solutions (pH 0-2).
• In solution, these acids dissociate into H+ ions and ions of conjugate base.

Acid-Base Reactions

• Basic, ionic oxides react with acids to produce a salt and water in a neutralization reaction.
• Acidic, covalent oxides react with bases to produce a salt and water in a neutralization reaction.
• Aluminium oxide (Al2O3) is amphoteric, meaning it can act as both an acid and a base.
• As a result, it can react with both acids and bases to form a salt and water in neutralization reactions.

Test your knowledge on the reactivity of Period 3 metals and their oxides. This quiz covers the formation of ions, reactivity trends, and the properties of various oxides formed by these elements. Perfect for students studying chemistry.