ionic bonding & compounds

• IONIC BONDING 


  It's the TRANSFER of electrons FROM a METAL atom TO a NON-metal atom.

  
• ionic bonding

  The METAL atom LOSES electrons to be a POSITIVELY charged ion, while the NON-METAL atom GAINS THOSE electrons to become a negatively charged ion.

  
• All ionic bonds has strong electrostatic forces holding each other, which is why they have high melting points - they need a lot of energy to break the forces.
• Lithium has ONE outer shell electron, and Fluorine has SEVEN.

  For BOTH atoms to get stability and a full outer shell is LITHIUM to TRANSFER ONE electron to FLUORINE.

  
• Lithium LOSES ONE electron and forms a positive ion and Fluorine gains one electron and forms a negative ion.

  • Both ions are OPPOSITELY CHARGED.

  The Li+ and F- join to give the final formula for Lithium Fluoride as LiF.

  
• Lithium has ONE outer shell electron, but Oxygen has SIX.

  Lithium LOSES ONE electron, but Oxygen GAINs TWO, so two Lithium atoms react with one oxygen atom to form ions with full outer shells.

  • The Li+ and O2- join to give the final formula for Lithium Oxide as Li2O.

  
• calcium loses 2 outer electrons to oxygen atoms and forms Ca2+

  oxygen gains 2 outer electrons to form O2-.

  Electrostatic forces of attraction pulls the ions together to form CaO.

  
• Magnesium loses two electrons and chlorine gains one electrons, so there's one magnesium and two chlorines and forms ionic bonds.

  
• Ionic compounds

  known for their GIANT IONIC LATTICE structure, which consists of a 3D arrangement where ions are held together by strong ELECTROSTATIC FORCES of attraction in ALL DIRECTIONS.

  
• Metals and Non-Metals that combine with IONIC BONDING form IONIC COMPOUNDS.
• Key Properties of Ionic Compounds

  HIGH MELTING AND BOILING POINTS:

  • since they have lattice structure that are held together by STRONG ELECTROSTATIC FORCES of attraction between the OPPOSITELY CHARGED ions, it will need a lot of energy to break.

  
• Key Properties of Ionic Compounds

  ELECTRICAL CONDUCTIVITY when molten or aqueous:

  • When ionic compounds are MOLTEN or AQUEOUS, the IONS are FREE TO MOVE, meaning they can CARRY A CHARGE and conduct electricity.

  
• Key Properties of Ionic Compounds

  ELECTRICAL CONDUCTIVITY when SOLID:

  • IONS in the solid are FIXED meaning the IONS are NOT free to move, so they CAN’T carry a charge and conduct electricity.

  
• Key Properties of Ionic Compounds

  SOLUBILITY:

  Many ionic compounds CAN DISSOLVE in water, allowing the ions to separate and move freely.
• Determining the Formula of an Ionic Compound:

  You can do this by SWAPPING the numbers of their charges and the amount of each element.

  • Calcium has a charge of +2 because it is in group 2.
  • Chlorine has a charge of -1 because it is in group 7.

  
• State how you can tell from a dot and cross diagram that the particles in a compound are held together by ionic bonds.

  The particles in a compound are oppositely charged ions. The bonds is formed by electrons transfer.

  
• Advantages of dots and cross diagrams:

  • charge of the ions
  • the arrangement of electrons in an atom or ion
  • which atoms the electrons in an ion originally come from
  • empirical formula (correct ratio of ions)

  
• disadvantages of dots and cross diagrams:

  • show the structure of the compound
  • correctly represent the size of the ions

  
• describe the structure of a crystal of sodium chloride.

  Sodium chloride crystal consists of sodium ions (Na+) and chloride ions (Cl-) arranged in a repeating 3D pattern with strong electrostatic forces holding them together.
• Ions:

  A charged particle formed from Atoms that has gained or lost electrons.
• DOT AND CROSS DIAGRAMS 

  represents the ARRANGEMENT of electrons in atoms or ions where each electron is a dot or a cross and shows where the electrons originally came from.
• Chemical bonds:

  • ionic bonds
  • covalent bonds
  • metallic bonds
• ionic bonds are the attraction between positive and negative ions.
• All alkalis has the same ion of OH-.
• All acids has the same ion of H+.
• Groups 1, 2, 6 & 7 form ions very easily.

  • Because they only need to gain or lose a small number of electrons, & so less energy is required. 

  Those in groups 3, 4 & 5 do not form ions very easily.

  • Because they need to gain or lose a larger number of electrons, & more energy is required.
• If the atom is becoming a positive ion & losing electrons.

  • Place the electron on the right of the reaction.

  If the atom is becoming a negative ion & gaining electrons.

  • Place the electron on the left to show that it’s combining with the atom.

  
• Electrostatic force:


  The force when Oppositely charged ions attract each other.

  • This force also attracts protons to electrons within atoms & ions.
• Hydroxide ion:  OH-
• Sulphate ion:

  $SO_4^{2-}$
• Nitrate ion:


  $NO_3^-$
• Carbonate ion:


  $CO_3^{2-}$
• Ammonium ion:


  $NH_4^+$
• Complex compounds, don’t have single elements:


  • Hydroxide
  • Sulphate
  • Nitrate
  • Carbonate
  • Ammonium
• Potassium ions have a 1+ charge, while carbonate ions have a 2- charge. 

  • Every carbonate ion will ionically bond with 2 potassium ions.
• Calcium hydroxide:


  $Ca^{2+}$ + $OH^-$ -> Ca(OH)$_2$
• Aluminium Sulphate:


  $Al_{ }^{3+}$ +$SO_4^{2-}$ -> $Al_2^{ }\left(SO_4^{ }\right)_3$
• Calcium sulphate:


  CaSO4