Formation of Ions

• What is an ion?


  An ion is a charged particle.
• How are ions formed?

  Ions are formed when atoms gain or lose electrons.
• Why do atoms form ions?

  Atoms form ions to have a full outer shell and become more stable.
• What does the group number in the periodic table indicate?

  The group number indicates how many electrons are in the outermost shell of the atoms in that group.
• How many electrons do group one elements have in their outermost shell?

  Group one elements have one electron in their outermost shell.
• How many electrons do group two elements have in their outermost shell?

  Group two elements have two electrons in their outermost shell.
• Why are group one and group two elements more likely to form ions?

  They require less energy to lose or gain one or two electrons.
• What type of ions do group one elements form?

  Group one elements form 1+ ions.
• What type of ions do group two elements form?

  Group two elements form two plus ions.
• What type of ions do group six elements form?

  Group six elements gain two electrons to become two minus ions.
• What type of ions do group seven elements form?

  Group seven elements gain one electron to become one minus ions.
• Why do elements in groups three, four, and five rarely form ions?

  They would have to lose or gain three or four electrons, which requires a lot of energy.
• How can we represent the formation of a sodium ion?

  A sodium atom goes to form a sodium ion plus an electron.
• How can we represent the formation of a chloride ion?

  Chlorine plus an electron forms a one minus chloride ion.
• Where do we place the electron in a reaction when an atom is becoming a positive ion?

  We place the electron on the right of the reaction.
• Where do we place the electron in a reaction when an atom is gaining electrons?


  We place the electron on the left to show that it's combining with the atom.
• How can we represent the formation of a magnesium ion?

  Mg goes to form Mg$^{2+}$ plus two electrons.
• How can we represent the formation of an oxygen ion?

  Oxygen plus two electrons goes to form an oxygen two minus ion.
• What is the process of forming ions from atoms?

  • Atoms gain or lose electrons.
  • They do this to achieve a full outer shell.
  • Group number indicates the number of outer electrons.
  • Group one and two elements easily form ions.
  • Groups three, four, and five rarely form ions due to high energy requirements.
• How do the energy requirements for forming ions differ among groups in the periodic table?

  • Group one: Lose one electron (low energy).
  • Group two: Lose two electrons (low energy).
  • Group six: Gain two electrons (moderate energy).
  • Group seven: Gain one electron (low energy).
  • Groups three, four, five: Lose or gain three or four electrons (high energy).