[5.2] ionic bonding and structure

Question 1

what is ionic bonding?

Answer 1

ionic bonding is the electrostatic force of attraction between oppositely charged ions

Question 2

how are ionic bonds formed?

Answer 2

• occurs between metal and non-metal elements
• electrons are transferred from the metal to the non-metal to form ions with the nearest noble gas electronic configuration

Question 3

structure of giant ionic lattices

Answer 3

• oppositely charged ions held in a regular 3D lattice by electrostatic attraction
• the arrangement of ions in a crystal lattice depends on the relative sizes of the ions
• ionic bonds occur in all directions

Question 4

what 2 factors affect the mp/bp of ionic compounds?

Answer 4

• ionic charge
• ionic radius

Question 5

how does ionic charge affect the mp/bp of ionic compounds?

Answer 5

greater charge means:

• stronger electrostatic force of attraction (stronger ionic bond)
• more energy will be required to break the strong ionic bonds
• higher mp/bp

Question 6

how does ionic radius affect the mp/bp of ionic compounds?

Answer 6

smaller ionic radius means:

• stronger electrostatic force of attraction (stronger ionic bond)
• more energy will be needed to break the strong ionic bonds
• higher mp/bp

Question 7

properties: solubility

Answer 7

• many ionic substances dissolve in polar solvents like water.
• polar water molecules break down the lattice and surround each ion in solution
• if the ions have large charges, the attraction between the ions may be too strong for the water to break down, and so will not be soluble in water.

Question 8

properties: electrical conductivity in solid state

Answer 8

solid ionic compounds do not conduct electricity because:

• the ions are in a fixed position in the giant ionic lattice
• so, there are no mobile charge carriers

Question 9

properties: electrical conductivity in liquid or aqueous state

Answer 9

molten or aqueous ionic compounds do conduct electricity because:

• the solid ionic lattice breaks down
• the ions are now free to move as mobile charge carriers.

Question 10

strength: brittle

Answer 10

• any dislocation leads to the layers moving and similar ions being adjacent
• the repulsion splits the crystal