Introductory Chemistry
Revell 1 SECoNo EDITION

Classify each atom based on whether it would gain or lose electrons to fulfill the octet rule.

Gain electrons

Lose electrons

Answer Bank
an atom in the halogen family
a calcium atom
an atom with an electron configuration of
an atom with an electron configuration of

1. An atom in the halogen family:
   • Halogens (Group 17) have 7 valence electrons. They need to gain 1 electron to achieve a full octet.
   • Classification: Gain electrons
2. A calcium atom:
   • Calcium (Ca) is in Group 2 and has 2 valence electrons. It tends to lose these 2 electrons to achieve a stable electron configuration (similar to noble gases).
   • Classification: Lose electrons
3. An atom with an electron configuration of :
   • This configuration corresponds to a Group 2 element (specifically, Radium, Ra). It has 2 valence electrons and will lose them to achieve a full octet.
   • Classification: Lose electrons
4. An atom with an electron configuration of :
   • This configuration corresponds to an element in Group 16 (specifically, Selenium, Se). It has 6 valence electrons and needs to gain 2 electrons to complete its octet.
   • Classification: Gain electrons

Summary:

• Gain electrons:
  • An atom in the halogen family
  • An atom with an electron configuration of
• Lose electrons:
  • A calcium atom
  • An atom with an electron configuration of