Electronic Structure

• Why do most atoms, like fluorine, have an incomplete outer shell of electrons?

  Because they need a full outer shell to be stable
• What must atoms do if they have an incomplete outer shell?

  They must react with another atom to gain or lose electrons
• How are electrons arranged around the nucleus of an atom?

  Electrons are arranged in shells around the nucleus
• How many electrons can the first shell hold?

  Two electrons
• How many electrons can the second shell hold?

  Up to eight electrons
• What do most atoms want to do to achieve stability?

  They want to react to form molecules or compounds
• What are the noble gases known for regarding their electron configuration?

  Noble gases have completely full outer shells
• What are the key points about electron arrangements in atoms?

  • Atoms need a full outer shell to be stable.
  • Electrons are arranged in shells around the nucleus.
  • The first shell holds 2 electrons, the second holds 8, and the third holds 8.
  • Atoms react to achieve a full outer shell.
  • Noble gases have full outer shells and do not react.
• How do you determine the electron arrangement for the first 20 elements in the periodic table?

  1. Identify the atomic number.
  2. Draw the nucleus.
  3. Fill the first shell with 2 electrons.
  4. Fill the second shell with 8 electrons.
  5. Fill the third shell with 8 electrons.
  6. If there are remaining electrons, place them in the next shell.
  7. Write the arrangement as numbers (e.g., 2, 8, 8).