1. METAL AQUA IONSSS

Coordinate bonds

involve one substance donating an electron pair to another

when metal compounds dissolve in water

the water molecules form coordinate bonds with the metal ions

metal-aqua complex ions

generally 6 water molecules form coordinate bonds with each metal ion

water molecules donate lone pair electrons from their oxygen

to form coordinate bonds

in a solution containing metal-aqua 2+ ions

there is a hydrolysis/ acidity reaction between the metal aqua ion and the water

metal aqua 2+ ion releases H⁺ Ions

so an acidic solution is formed

the solution is only weakly acidic

there is only slight dissociation

metal 3+ ions are smaller but have a high charge

this gives them a high charge density (charge/size ratio)

metal 2+ ions have a lower charge density

this makes 3+ ions more polarising than 2+ ions

more polarasing power

means that they attract electrons from oxygen atoms of a coordinate bod more strongly,

more polarising power weakens O-H bonds

so its more likely H⁺ ions are released

the more hydrogen ions releases the more acidic the solution

3+ metal ions are more acidic than 2+ metal ions