Ionic bonding
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Describe the difference in electronegativities of elements in ionically bonded compounds
They tend to have large differences between the two
What effect does ionic bonding have on the atomic radii of the cations
It decreases them because the loss of outer energy level electrons results in the loss of the energy level as well as an increased effective nuclear charge, pulling in the remaining electrons
What effect does ionic bonding have on the atomic radii of the anions
It increases them because gaining electrons means a decreased effective charge
How are ionic structures held together
As giant ionic lattices, where cations and anions are arranged alternately and are held together by directional electrostatic attractions
What is a crystal co-ordination number
The maximum number of cations than can surround an anion without causing repulsion and vice versa
What is the crystal co-ordination number of sodium chloride
6:6
What is the crystal co-ordination number of caesium chloride
8:8
Why has caesium chloride got a higher crystal co-ordination number than sodium chloride
Because caesium is much larger than sodium
Why are ionic substances brittle
shifting the ions causes them to repel each other and lattice breaks
Why do ionic substances have a high melting/boiling point
breaking the strong electrostatic attractions requires lots of energy
Why do ionic substances conduct electricity when molten or as an electrolyte
The electrons can move more easily and transport an electrical current
Why are ionic substances generally soluble
They have positive and negative charges which water can split apart.
Are group one salts soluble
always
Are ammonium salts soluble
always
Are nitrate salts soluble
always
Are halide salts soluble
Yes except with silver or lead cations
Are sulphate salts soluble
Yes except with lead and lower group 2
Are hydroxide salts soluble
No except with group 1, lower group 2 and ammonium cations
Are carbonate salts soluble
No except with group 1 and ammonium cations