Periodicity

• Which elements are included in Period 3?

  Sodium to Argon
• What is important to know about electron configurations?

  They apply to Period 3 elements
• How does the electron configuration change across Period 3?

  One electron is added each time
• What is the electron configuration for Sodium?

  1s² 2s² 2p⁶ 3s¹
• What is the electron configuration for Argon?

  1s² 2s² 2p⁶ 3s² 3p⁶
• What blocks are present in the periodic table?

  S, P, D, and F blocks
• What does the filling of orbitals indicate?

  Which block the element belongs to
• How does atomic radius change across Period 3?

  Atomic radius decreases across the period
• Why does atomic radius decrease across Period 3?

  More protons create stronger attraction
• What happens to atomic size when moving down a group?

  Atomic size increases down the group
• What is ionization energy?

  Energy required to remove an electron
• How does ionization energy change across Period 3?

  Ionization energy generally increases across the period
• What causes the increase in ionization energy across Period 3?

  More protons lead to stronger electron attraction
• What is the trend in ionization energy between Magnesium and Aluminium?

  Aluminium has lower ionization energy than Magnesium
• Why does ionization energy decrease from Phosphorus to Sulfur?

  Repulsion from paired electrons makes removal easier
• What is the trend in melting and boiling points across Period 3?

  No general trend; varies by bonding
• What are the key trends across Period 3 elements?

  • Atomic radius decreases
  • Ionization energy generally increases
  • Melting and boiling points vary
• What factors affect atomic radius in Period 3?

  • Same energy level across the period
  • Increased nuclear charge with more protons
  • No additional shielding from inner shells
• What factors affect ionization energy in Period 3?

  • Increased nuclear charge with more protons
  • Electron shielding effects
  • Electron repulsion in paired orbitals
• What is the significance of electron configurations in Period 3?

  • Determines chemical properties
  • Influences atomic size and ionization energy
  • Indicates block classification in the periodic table
• What is the general trend in ionization energies across a period?

  Ionization energies generally increase across a period.
• Which elements are mentioned in the study material?

  Sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, argon
• What primarily causes the changes in melting and boiling points across the period?

  The changes are due to bonding types.
• What types of bonding are present in sodium, magnesium, and aluminium?

  • Metallic bonding
  • Strong attraction between positive ions and delocalized electrons
• What type of bonding is present in silicon?

  Silicon has macromolecular covalent bonding.
• Why does silicon have a high melting point?

  It requires a lot of energy to break covalent bonds.
• What is the bonding type in phosphorus, sulfur, and chlorine?

  Simple molecular covalent bonding.
• What are the molecular forms of phosphorus, sulfur, and chlorine?

  Phosphorus is P₄, sulfur is S₈, chlorine is Cl₂.
• What type of forces exist between the molecules of phosphorus, sulfur, and chlorine?

  Van der Waals forces exist between the molecules.
• How does the size of a molecule affect van der Waals forces?

  Larger molecules have stronger van der Waals forces.
• Why does chlorine have a lower melting point than sulfur and phosphorus?

  Chlorine is a smaller molecule with weaker forces.
• What type of bonding does argon exhibit?

  Argon exhibits weak van der Waals forces.
• Why does argon have a lower melting point than chlorine?

  Argon is monatomic with very weak forces.
• Summarize the trends in melting and boiling points across the period.

  • Metallic bonding increases melting/boiling points (sodium to aluminium).
  • Silicon has high melting/boiling points due to strong covalent bonds.
  • Phosphorus, sulfur, and chlorine have lower melting/boiling points due to simple molecular structures.
  • Argon has the lowest melting/boiling point due to weak van der Waals forces.
• What is the significance of knowing the molecular forms of phosphorus, sulfur, and chlorine?

  It helps predict their physical properties.
• How does the strength of metallic bonding change from sodium to aluminium?

  The strength of metallic bonding increases due to higher charges.
• What is the relationship between the number of delocalized electrons and melting/boiling points?

  More delocalized electrons lead to higher melting/boiling points.
• What is the trend in melting points from sodium to argon?

  Melting points increase then decrease across the period.
• Why is it important to understand the types of bonding present in elements across a period?

  It helps explain their physical and chemical properties.
• What happens to the melting and boiling points as you move from metals to nonmetals across the period?

  They generally increase then decrease.