Ionic Bonding

• Noble gases


  Atoms with fully filled valence shells of electrons, inert and exist as monoatomic gases
• Noble gases and their electronic configurations

  • Helium (2)
  • Neon (2, 8)
  • Argon (2, 8, 8)
• Atoms that are not noble gases

  Lose, gain or share electrons to fill up their outermost electron shells
• Positive ion (cation)


  Formed when an atom (usually a metal) loses electron(s), has a net positive charge and usually has a noble gas electronic configuration
• Negative ion (anion)


  Formed when an atom (usually a non-metal) gains electron(s), has a net negative charge and has a noble gas electronic configuration
• Common cations


  • Hydrogen (H+)
  • Sodium (Na+)
  • Potassium (K+)
  • Silver (Ag+)
  • Ammonium (NH4+)
  • Magnesium (Mg2+)
  • Calcium (Ca2+)
  • Barium (Ba2+)
  • Iron(II) (Fe2+)
  • Copper(II) (Cu2+)
  • Zinc (Zn2+)
  • Lead(II) (Pb2+)
  • Iron(III) (Fe3+)
  • Lead(III) (Pb3+)
• Hydrogen ion


  A proton with no electrons, the only element that forms an ion with no electrons
• Ammonium ion


  A polyatomic ion made up from more than one atom, consisting of non-metallic elements
• Common anions


  • Fluoride (F-)
  • Chloride (Cl-)
  • Bromide (Br-)
  • Iodide (I-)
  • Hydroxide (OH-)
  • Nitrate (NO3-)
  • Manganate(VII) (MnO4-)
  • Oxide (O2-)
  • Carbonate (CO32-)
  • Sulfate (SO42-)
  • Phosphate (PO43-)
• Halide ions


  Anions formed by Group 17 elements
• Polyatomic ions


  Ions made up from more than one atom
• Ionic bond


  The mutual electrostatic attraction between ions of opposite charges
• Ionic compound


  An electrically neutral compound where the total positive charge from the positive ions equals the total negative charge from the negative ions
• Ionic structure


  A 3D structure of alternating cations and anions called a giant ionic crystal lattice
• Covalent bond


  Formed when atoms share electrons to attain noble gas electronic configurations
• Valency


  The number of electron(s) that must be lost, gained or shared in order for an atom to attain a noble gas electronic configuration
• Covalent molecule


  Made from atoms of the same or different elements
• Simple molecules


  • Have a countable number of atoms in a fixed ratio, e.g. water and wax
• Giant molecules


  • Have a practically uncountable number of atoms, e.g. diamond and sand (silicon dioxide)
• Determining number of covalent bonds

  Compare the valences of the atoms
• Metallic bond

  The mutual electrostatic forces of attraction between positively charged ions in a metal and the "sea of mobile (or delocalised) electrons"
• Aluminium has 3 valence electrons, vanadium has 5 valence electrons


  Vanadium has a higher melting point than aluminium
• The number of electrons determines the charge on an ion.
• Cations have fewer electrons than protons, while anions have more electrons than protons.
• Ions are charged particles formed when atoms gain or lose electrons.
• Ions are formed when one or more electrons are transferred from one atom to another.
• Ions are formed when one or more outer shell electrons are lost from an atom to form a positive ion (cation), or gained by an atom to form a negative ion (anion).
• When two oppositely charged ions come together, they form an ionic compound.
• Group 1 elements lose their outermost electron(s) easily due to having only one electron in that shell.
• Group 2 elements also lose their outermost electron(s) but require more energy compared to Group 1 elements.
• Atoms with low atomic numbers tend to form positive ions by losing electrons, while those with high atomic numbers tend to form negative ions by gaining electrons.
• When two oppositely charged ions come together, they attract each other due to their opposite charges.
• In ionic compounds, there is no net overall charge because the total number of positive charges equals the total number of negative charges.
• A cation is a positive ion that results from the loss of one or more electrons by an atom or group of atoms.
• An anion is a negative ion that results from the gain of one or more electrons by an atom or group of atoms.
• Atoms can form ions through electron transfer reactions with other elements.
• Metals tend to lose electrons to become positively charged cations, while non-metals tend to gain electrons to become negatively charged anions.
• An ion is an electrically charged particle that results from the loss or gain of electrons by an atom.
• A cation is a positively charged ion formed when an atom loses one or more electrons.
• The number of valence electrons determines the charge on the cation.