ions, ionic bonding, and ionic compounds

• ions are charged particles
• atoms lose/gain electrons to gain a full outer shell of electrons.
• negative ions

  anions
• positive ions

  cations
• anion - gain of electrons
• cation - loss of electrons
• the number of electrons lost/gained is the same as the charge
• groups 1, 2, 6 and 7 are most likely to form ions.
• group 1 and 2 elements are metals. they lose electrons to form positive ions.
• group 6 and 7 elements are non-metals. they gain electrons to form negative ions.
• elements in the same group all have the same number of outer electrons. so, they form ions with the same charges.
• group 1, 1+

  group 2, 2+

  group 6, -2

  group 7, -1
• ionic compounds are made up of a positively charged part and a negatively charged part. the overall charge of any ionic compound is zero. so all the negative charges must balance the positive charges.
• when a metal reacts with a non-metal, the metal atom loses electrons to form a positive ion and the non-metal gains these electrons to form a negative ion. the oppositely charged forces are strongly attracted to each other by electrostatic forces. this attraction is known as an ionic bond.
• dot and cross diagrams are used to show the arrangement of electrons in an atom or ion. each electron is represented by a dot or a cross.
• ionic compounds always have giant ionic lattice structures. the ions form a closely packed regular lattice. there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions.
• ionic compounds properties

  • have high melting and boiling points due to the strong attraction between ions. takes a large amount of energy to overcome this attraction.
  • solid ionic compounds don’t conduct electricity because the ions are in a fixed position. when melted, the ions are free to move and will carry an electric charge.
  • many also dissolve easily in water. the ions separate and are all free to move in the solution, so they’ll carry an electric charge.