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GROUP 1A : ALKALI METALS & THEIR COMPOUNDS - Coggle Diagram
GROUP 1A : ALKALI METALS & THEIR COMPOUNDS
SOLUBILITY
If endothermic → ΔH latt high= insoluble
dissolved in water ( hydration towards free ions involves released energy E(-ve) [M+ + X- → M+ + X- ; E(-VE)]
Properties
Physical
Melting point decreases down the group
Density decreases down the group
Kept in oil to avoid oxidation
Ionisation energy,IE decreases down the group
Electron affinity,EA decreases down the group (magnitude)
Soft metal with silvery colour
Good thermal/ electrical conductor
General
Extremely reactive
act as electron donor
Reactivity increase down the group ( ↑size ↑ shielding effect ↓ ionizatin energy)
Exist as ionic compound ,↑ melting points when in compound ,soluble in water, conduct electricity
Chemical
Wet Air (O2,CO2,H2O)
slow to form oxide→hydroxide→carbonate [3X + O2 → 2M2O] [M2O + H2O → 2MOH] 2MOH + CO2 + nH2O → M2CO3.nH2O
H2O (very reactive, h2 evolve, base solution) X + 2H20 → 2MOH + H2 (X= Li<Na<K<Rb<Cs)
alkali metals
2X + 2H2O → 2XOH + H2 (X= Li,Na,K..)
Have 1 electron valence
Li,Na,K,Rb,Cs,Fr
Compounds of alkali metals
HYDROXIDE
NaOH used in the manufacture of synthetic fibers,soaps and detergents.
Obtaining pure Al2O3 from bauxite
Electrolysis
Bleaching agent
NITRATES
NaNO3 - Deliquescent solid ,used in making fertiliser
KNO3 - Naturally occur as mineral saltpetre, used in manufacturing fertilizer
HYDRIDES
React violantly with water [MH + H2O → MOH + H2]
Reaction with alcohol → alcoholate [MH + ROH → MOR + H2]
colouless ionic crystal
Uses as reducing agent (NaBH4 is more selective reducing agent than LiALH4)
positive, negative @ aloi
CARBONATE
Na2CO3 (colourless transparent solid) used in glass manufacturing industries Manufacturing of soap and detergent
K2CO3 Used in preparation of soft soap ,Manufacturing glass and ceramic ,Drying agent for organic solvent
Solvay process (ammonia absorber tower ,Limestone Furnace ,Ammonia supply tower ,Carbonate converter)
OXIDES
ionic solid crystals
as bleaching agent
monoxide( 4M + O2 → 2M2O [ CONDITION : 180 °C] peroxide (2M + O2 → M2O2 [ CONDITION : 300°C] superxide (M + O2 → MO2 [ CONDITION : 300°C]
monoxide, peroxide, superoxide
Thermal and solubility of salt of group IA
Compound that contain ions with widely different radii are soluble
Due to the decrease in lattice energy,ΔH latt is bigger than the decreasing in hydration energy,ΔHsolv
Li2CO3 - decompose upon heating
Lithium is anomalous due to its small ionic radius and tendency to exhibit covalent bonding
Form normal oxide
Exhibit covalent character ( high polarizing power associated with high charge density
APPLICATIONS
Sodium - produces yellow glow uses as coolant in reactor
Potassium - to produce soft liquid soap - used as fertilisers and used in metal extraction