Period 3

• Which elements are discussed in their reactions with water?

  Sodium and magnesium
• What happens when sodium reacts with cold water?

  It fizzes around on the surface
• What is the 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?

  Very slowly with cold water, readily with steam
• What is the 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 reacting with oxygen?

  Oxides
• What color flame does sodium produce when burned in oxygen?

  Yellow flame
• What is produced when magnesium, aluminum, silicon, and phosphorus burn in oxygen?

  White solid smoke
• What color flame does sulfur produce when burned in oxygen?

  Blue flame
• What is the equation for sodium reacting with oxygen?

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

  2 Mg (s) + O2 (g) → 2 MgO (s)
• What is the equation for aluminum reacting with oxygen?

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

  Si (s) + O2 (g) → SiO2 (s)
• What is the equation for phosphorus reacting with oxygen?

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

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

  • Ionic oxides (e.g., Na2O, MgO, Al2O3)
  • Macromolecular oxides (e.g., SiO2)
  • Simple molecular oxides (e.g., P4O10, SO2, SO3)
• Why do ionic oxides have high melting points?

  Strong forces between oppositely charged ions
• What type of structure do ionic oxides have?

  Giant lattice structures
• What causes the increased melting points from Na to Al in ionic oxides?

  Increased charge on the cation
• What character does Al2O3 exhibit?

  Some covalent character
• What type of bonding does SiO2 have?

  Strong covalent bonds
• Why do simple molecular oxides have lower melting points?

  Weak intermolecular forces between molecules
• What is the formula for P4O10?

  4 P's and 10 O's
• How can you experimentally prove that compounds contain ions?

  Melt the solids and show they conduct electricity
• How does aluminum oxide protect aluminum from corrosion?

  Forms a thin impermeable layer
• Why is sodium stored under oil?

  To prevent reaction with air
• What do basic oxides react with to form salts?

  Acids
• What is the equation for sodium oxide reacting with hydrochloric acid?

  Na2O (s) + 2 HCl (aq) → 2 NaCl (aq) + H2O (l)
• What is the equation for magnesium oxide reacting with hydrochloric acid?

  MgO (s) + 2 HCl (aq) → MgCl2 (aq) + H2O (l)
• What is the pattern for acid-base reactions involving oxides?

  Acid + base → salt + water
• What is an amphoteric oxide?

  Can act as both an acid and an alkali
• What is the equation for aluminum oxide acting as a base?

  Al2O3 (s) + 3 H2SO4 (aq) → Al2(SO4)3 (aq) + 3 H2O (l)
• What is the 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 dissolve in water?

  It has a giant covalent structure
• What is the equation for SiO2 reacting with concentrated NaOH?

  2 NaOH (l) + SiO2 (s) → Na2SiO3 (aq) + H2O
• What is the equation for P4O10 reacting with NaOH?

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

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

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

  Whether to provide ionic or full equations
• What happens to the pH of solutions across the period?

  Changes from basic to acidic