Electron configuration

• What is electronic structure concerned with?


  How electrons are arranged in atoms
• What are electron shells in the atom?


  Regions where electrons move around the nucleus with fixed energies
• What is the principal quantum number for the 1st electron shell?


  1
• How does the energy of an electron shell change with distance from the nucleus?


  The further a shell is from the nucleus, the higher its energy
• Which electron shell has the highest energy?


  The 3rd electron shell
• What are sub-shells in the atomic model?


  Divisions within shells that have different energies
• What types of sub-shells exist?


  s, p, d, and f sub-shells
• How many sub-shells does the 1st shell contain?


  One sub-shell, 1s
• How many sub-shells does the 4th shell contain?


  Four sub-shells: 4s, 4p, 4d, and 4f
• How do you calculate the maximum number of electrons in a sub-shell?


  By multiplying the number of orbitals by 2
• How many electrons can the 3rd shell hold?


  18 electrons
• What is the maximum number of electrons each sub-shell can hold?


  • s: 2 electrons
  • p: 6 electrons
  • d: 10 electrons
  • f: 14 electrons
• What does the notation 2p represent?


  The 2p sub-shell in the 2nd electron shell
• What is the electron configuration of a magnesium atom (Mg)?


  1s² 2s² 2p⁶ 3s²
• What happens to the electron configuration of an ion from the s and p blocks?


  Electrons are added or removed from the highest energy occupied sub-shell
• How does the electron configuration of chromium differ from the expected configuration?


  It is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹ instead of 3d⁶ 4s²
• What is the electron configuration of copper and why is it unusual?


  It is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹ due to stability of a full d sub-shell
• What is the electron configuration of an Fe atom?


  1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²
• What happens to the electron configuration of transition metals when they become ions?


  They lose their 4s electrons before their 3d electrons
• How do outer shell electrons affect an element's chemical properties?


  The number of outer shell electrons determines the chemical properties
• What are the characteristics of s block elements?


  • Have 1 or 2 outer shell electrons
  • Easily lose electrons to form positive ions
  • Achieve an inert gas configuration
• What are the characteristics of p block elements?


  • Can gain 1, 2, or 3 electrons to form negative ions
  • Can share electrons to form covalent bonds
  • Groups 5, 6, and 7 in the periodic table
• What is the first ionisation energy?


  The energy required to remove the outermost electron from an atom
• What factors affect ionisation energy?


  Nuclear charge, distance from the nucleus, and electron shielding
• How does nuclear charge affect ionisation energy?


  A higher nuclear charge increases the attraction between the nucleus and electrons
• How does distance from the nucleus affect ionisation energy?


  Ionisation energy decreases as the distance from the nucleus increases
• What is electron shielding?


  When inner electrons reduce the effective nuclear charge felt by outer electrons
• What is the maximum number of electrons the 4th shell can hold?


  32 electrons
• What is the electron configuration of a chlorine atom (Cl)?


  1s² 2s² 2p⁶ 3s² 3p⁵
• What is the electron configuration of a chloride ion (Cl⁻)?


  1s² 2s² 2p⁶ 3s² 3p⁶
• What is the electron configuration of a calcium atom (Ca)?


  1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
• What is the electron configuration of a calcium ion (Ca²⁺)?


  1s² 2s² 2p⁶ 3s² 3p⁶