Period 3

• Which elements are discussed in the reactions with water?

  Sodium (Na) and Magnesium (Mg)
• What happens when sodium reacts with cold water?

  Sodium fizzes around on the surface and produces sodium hydroxide and hydrogen gas.
• What is the chemical equation for sodium reacting with water?

  2 Na (s) + 2 H2O (l) → 2 NaOH (aq) + H2 (g)
• How does magnesium react with cold water compared to steam?

  Magnesium reacts very slowly with cold water but more readily with steam to form magnesium oxide.
• What is the chemical equation for magnesium reacting with steam?

  Mg (s) + H2O (g) → MgO (s) + H2 (g)
• What do all the elements Na, Mg, Al, Si, P, and S form when they react with oxygen?

  They all react with oxygen to form oxides.
• What color flame does sodium produce when it burns in oxygen?

  Sodium burns with a yellow flame.
• What is produced when sodium burns in oxygen?

  A white solid, sodium oxide.
• What color flame do magnesium, aluminum, silicon, and phosphorus produce when they burn in oxygen?

  They burn with a white flame.
• What is the chemical equation for sodium burning in oxygen?

  4 Na (s) + O2 (g) → 2 Na2O (s)
• What is the chemical equation for magnesium burning in oxygen?

  2 Mg (s) + O2 (g) → 2 MgO (s)
• What is the chemical equation for aluminum burning in oxygen?

  4 Al (s) + 3 O2 (g) → 2 Al2O3 (s)
• What is the chemical equation for silicon burning in oxygen?

  Si (s) + O2 (g) → SiO2 (s)
• What is the chemical equation for phosphorus burning in oxygen?

  4 P (s) + 5 O2 (g) → P4O10 (s)
• What is the chemical equation for sulfur burning in oxygen?

  S (s) + O2 (g) → SO2 (g)
• What are the types of oxides formed by Period 3 elements and their properties?

  • Ionic oxides (e.g., Na2O, MgO, Al2O3):
  • High melting points
  • Ionic giant lattice structures
  • Macromolecular oxides (e.g., SiO2):
  • Very high melting and boiling points due to strong covalent bonds
  • Simple molecular oxides (e.g., P4O10, SO2):
  • Lower melting points due to weak intermolecular forces
• Why do ionic oxides have high melting points?

  They have strong forces of attraction between oppositely charged ions.
• How does the charge on the cation affect the melting point of ionic oxides?

  Increased charge on the cation leads to stronger ionic forces and higher melting points.
• What character does aluminum oxide exhibit and why?

  Aluminum oxide shows some covalent character due to the small aluminum ion being able to distort the oxide charge cloud.
• What is the structure of silicon dioxide (SiO2)?

  SiO2 has a giant covalent structure with very strong bonds.
• Why does SiO2 not dissolve in water?

  SiO2 does not dissolve in water due to its giant covalent structure and strong bonds.
• What is the chemical equation for SiO2 reacting with concentrated NaOH?

  2 NaOH (l) + SiO2 (s) → Na2SiO3 (aq) + H2O (l)
• What are the properties of simple molecular oxides like P4O10 and SO2?

  • Simple molecular oxides have weak intermolecular forces.
  • They have lower melting points compared to ionic and macromolecular oxides.
  • P4O10 is larger and has more electrons than SO2, leading to larger van der Waals forces and a higher melting point.
• How can you experimentally prove that certain compounds contain ions?

  By melting the solids and showing they conduct electricity.
• How does aluminum oxide protect aluminum metal from corrosion?

  It forms a thin layer that is impermeable to air and water due to its high lattice strength and insolubility in water.
• Why is sodium stored under oil?

  Sodium is stored under oil to prevent it from reacting with air.
• What is the general reaction pattern for basic oxides with acids?

  Acid + Base → Salt + Water
• What is an amphoteric oxide?

  An amphoteric oxide can act as both an acid and a base.
• What is the chemical equation for aluminum oxide acting as a base?

  Al2O3 (s) + 3 H2SO4 (aq) → Al2(SO4)3 (aq) + 3 H2O (l)
• What is the chemical equation for aluminum oxide acting as an acid?

  Al2O3 (s) + 2 NaOH (aq) + 3 H2O (l) → 2 NaAl(OH)4 (aq)
• Why does SiO2 not react with weak solutions of alkali?

  SiO2 does not react with weak solutions of alkali due to its strong covalent bonds.
• What is the chemical equation for P4O10 reacting with sodium hydroxide?

  P4O10 (s) + 12 NaOH (aq) → 4 Na3PO4 (aq) + 6 H2O (l)
• What is the chemical equation for SO2 reacting with sodium hydroxide?

  SO2 (g) + 2 NaOH (aq) → Na2SO3 (aq) + H2O (l)
• What is the chemical equation for SO3 reacting with sodium hydroxide?

  SO3 (g) + 2 NaOH (aq) → Na2SO4 (aq) + H2O (l)
• What should you be careful about when answering questions regarding chemical equations?

  You should be careful whether the question is asking for an ionic equation or a full equation.
• What is the change in pH when metal ionic oxides react with water?

  They form hydroxides which are alkaline, resulting in a high pH.
• What is the pH of the solution formed when sodium oxide reacts with water?

  The pH is 13, indicating a vigorous exothermic reaction.
• What is the pH of the solution formed when magnesium oxide reacts with water?

  The pH is 9, indicating it is only slightly soluble in water.
• Why do Al2O3 and SiO2 not dissolve in water?

  They do not dissolve due to the high strength of the Al2O3 ionic lattice and the SiO2 macromolecular structure.
• What is the pH of the solution formed when P4O10 reacts with water?

  The pH is 0, indicating a vigorous exothermic reaction.