Formation of Ions

• What is an ion?

  A charged particle
• How are ions formed?

  Atoms gain or lose electrons
• Why do atoms form ions?

  To have a full outer shell for stability
• What does the group number in the periodic table indicate?

  Electrons in the outermost shell
• How many electrons do group one elements have in their outermost shell?

  One electron
• How many electrons do group two elements have in their outermost shell?

  Two electrons
• Why are group one and two elements more likely to form ions?

  They require less energy to lose or gain electrons
• What ion do group one elements form?

  One plus ions
• What ion do group two elements form?

  Two plus ions
• What ion do group six elements form?

  Two minus ions
• What ion do group seven elements form?

  One minus ions
• Why do elements in groups three, four, and five rarely form ions?

  They require a lot of energy to lose or gain electrons
• What is the chemical equation for sodium forming a sodium ion?

  Na → Na⁺ + e⁻
• What is the chemical equation for chlorine forming a chloride ion?

  Cl + e⁻ → Cl⁻
• Where do we place the electron in the equation for losing electrons?

  On the right of the reaction
• Where do we place the electron in the equation for gaining electrons?

  On the left of the reaction
• What is the equation for magnesium forming a magnesium ion?

  Mg → Mg²⁺ + 2e⁻
• What is the equation for oxygen forming an oxide ion?

  O + 2e⁻ → O²⁻
• What are the general trends for ion formation in the periodic table?

  • Group 1: Lose 1 electron (1+ ion)
  • Group 2: Lose 2 electrons (2+ ion)
  • Group 6: Gain 2 electrons (2- ion)
  • Group 7: Gain 1 electron (1- ion)
  • Groups 3, 4, 5: Rarely form ions due to high energy requirement
• How do the energy requirements for ion formation differ among groups in the periodic table?

  • Groups 1 and 2: Low energy to lose electrons
  • Groups 6 and 7: Moderate energy to gain electrons
  • Groups 3, 4, 5: High energy to lose or gain electrons