Determine the group number of bromine. Provide the number of electrons each of its shells holds and the electron configuration in its valence shell.

• A. Bromine is in Group 7A.
  Shell number 1 contains 2 electrons.
  Shell number 2 contains 8 electrons.
  Shell number 3 contains 18 electrons.
  Shell number 4 contains 7 electrons.
  The electron configuration of the valence shell of bromine is 4s²4p⁵.
• B. Bromine is in Group 6A.
  Shell number 1 contains 2 electrons.
  Shell number 2 contains 8 electrons.
  Shell number 3 contains 18 electrons.
  Shell number 4 contains 6 electrons.
  The electron configuration of the valence shell of bromine is 4s²4p⁴.
• C. Bromine is in Group 7A.
  Shell number 1 contains 2 electrons.
  Shell number 2 contains 8 electrons.
  Shell number 3 contains 18 electrons.
  Shell number 4 contains 7 electrons.
  The electron configuration of the valence shell of bromine is 5s²5p⁵.
• D. Bromine is in Group 6A.
  Shell number 1 contains 2 electrons.
  Shell number 2 contains 8 electrons.
  Shell number 3 contains 18 electrons.
  Shell number 4 contains 6 electrons.
  The electron configuration of the valence shell of bromine is 5s²5p⁴.

Answer: (A)