💧 LOW-T TOPIC 6: HYDRATION, IONIC RADIUS & POTENTIAL

Hydration shell definition

structured water around ions

Hydration energy meaning

controls ion mobility and reactivity

Ionic radius relevance

smaller ions bind water more strongly

Ionic potential definition

charge-to-radius ratio

Structure-making ions

enhance water structure

Structure-breaking ions

disrupt water structure

Link to mineral–water interaction

hydration affects adsorption and desolvation

Fun exam fact

highly hydrated ions sorb less easily

Diagram card – Hydration

ion surrounded by oriented water molecules

Primary hydration shell,

innermost layer of tightly bound water molecules directly coordinated to an ion

Secondary hydration shell,

outer layer of more loosely bound water molecules influenced indirectly by the ion

Relationship between ionic radius and hydration,

smaller ions bind water more strongly due to higher charge density

Relationship between charge and hydration,

ions with higher charge attract water molecules more strongly and have higher hydration energies

Low ionic potential ions,

large low-charge ions interact weakly with water and remain highly mobile

High ionic potential ions,

small highly charged ions strongly interact with water and surfaces

Hydration and diffusion,

strongly hydrated ions diffuse more slowly through water

Hydration and complexation,

hydration competes with ligand binding and affects complex stability

Hydration and pH effects,

pH controls protonation which alters hydration behaviour

Mg²⁺

is strongly hydrated which explains slow dolomite precipitation