properties of period 3

• What do melting and boiling points reflect across period 3?

  Structure and bonding
• How do bonds affect melting and boiling points of elements across period 3?

  They determine the strength of attraction between atoms
• What is the trend in melting and boiling points for metals in period 3?

  • Increases across the period
  • Due to increasing strength of metallic bonding
• Why does the strength of metallic bonding increase across period 3?

  Due to larger positive charge and smaller ionic radius
• How many delocalised electrons does sodium have per ion?

  1 delocalised electron
• How many delocalised electrons does aluminium have per ion?

  3 delocalised electrons
• What is the structure of silicon (Si)?

  Giant covalent lattice structure
• How many neighboring atoms is each silicon atom covalently bonded to?

  4 neighboring atoms
• What arrangement do silicon atoms form in their lattice structure?

  Tetrahedral arrangement
• Why does silicon have a high melting and boiling point?

  Strong covalent bonds require a lot of energy to break
• What are the structures of phosphorus, sulfur, and chlorine in period 3?

  • Phosphorus (P4): Simple molecular structure
  • Sulfur (S8): Simple molecular structure
  • Chlorine (Cl2): Simple molecular structure
• What type of forces exist between the molecules of phosphorus, sulfur, and chlorine?

  Weak induced dipole-dipole forces
• Why does sulfur (S8) have the highest melting and boiling points among P4, S8, and Cl2?

  It has more electrons, allowing stronger forces
• Why does chlorine (Cl2) have the lowest melting and boiling points?

  It has the fewest electrons, resulting in weak forces
• What is the melting and boiling point of argon (Ar)?

  Lowest among period 3 elements
• Why does argon (Ar) have low melting and boiling points?

  Weak induced dipole-dipole forces require minimal energy
• What is the trend in atomic radius across period 3?

  • Decreases across the period
  • Due to increasing nuclear charge and minimal shielding
• Why does atomic radius decrease across a period?

  Stronger attraction between nucleus and outer electrons
• What happens to the electrons added across a period?

  They go into the outer energy level
• How does increased nuclear charge affect atomic radius?

  It causes the atomic radius to decrease
• What is the effect of minimal change in shielding on atomic radius?

  It contributes to the decrease in atomic radius