• Dot and cross diagrams?are diagrams that show the arrangement of the outer-shell electrons in an?ionic?or?covalent?compound or element
  • The electrons are shown as dots and crosses

   

• In a dot and cross diagram:
  • Only the outer electrons are shown
  • The charge of the ion is spread evenly which is shown by using brackets
  • The charge on each ion is written at the top right-hand corner

   

Ionic compounds

• Ionic bonds are formed when?metal atoms?transfer electrons to a?non-metal?to form a positively charged and negatively charged ion
• The atoms achieve a?noble gas?configuration

Dot-and-cross diagrams of ionic compounds in which one of the atoms transfers their valence electrons to the other

Covalent compounds

• The atoms in covalent compounds will?share?their outer valence electrons to achieve a?noble gas?configuration

Dot-and-cross diagrams of covalent compounds in which the atoms share their valence electrons

Answer

• • Lithium is a Group 1 metal, so it loses its 1 electron from its outer shell
  • This forms a Li+?ion
  • Nitrogen is a Group 5 non-metal, so it needs to gain 3 electrons to complete its outer shell
  • This forms an N3-?ion
  • Overall, three lithium atoms each donate an electron to one nitrogen atom, to form 3 x?Li+?ions and 1 x?N3-
  • The overall ionic compound formed is?Li3N