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GROUP IIA ALKALINE METALS & THEIR COMPOUNDS - Coggle Diagram
GROUP IIA ALKALINE METALS & THEIR COMPOUNDS
INTRODUCTION
Found in earth's crust (mineral)
Electron Configuration = number of shell increase, shielding increases, atomic radius increases ,1st ionisation energy decreases
Dissolve in water, form basic solutions
Form positive ions (cations)
Be, Mg, Ca, Sr, Ba, Ra
ANAMALOUS PROPERTIES OF Be
strong Lewis acid
Coordination number = 4
High charge density, high polarizing power, mostly covalent
Only Be undergo extraction
Undergo hydrolysis to form acidic solution
High tendency form complexes
PROPERTIES
PHYSICAL
soft but harder compared to other alkali metals
Grey white luster in colour when freshly cut
hardness decreases down the group
Form metallic bonding = 2 valence electron binding the metallic lattice together
Will form thin oxide coating when exposed to air
CHEMICAL
ACID
M + acid → MCL2 + H2
Reaction more vigorous as we go down the group
REDUCING AGENTS
M + reducing agents → pure element
Reduction of the oxides and chlorides of B,Ti,Zr etc by Mg & Ca
H2O
Reactivity of metal increases down the group
Halogen , X2 : M + X2 → MX2(ionic halides)
M (except Be) + 2H2O → M(OH)2 + H2
H2O (g) = rapid process
H2
M + H2 → MH2(hydride)
O2
M + O2 → binary oxide
does not form superoxide
down the group will burn vigorously
REDOX REACTION (metal oxidised & oxygen reduction)
N2
3M + N2 → (M3N2)nitride
DIAGONAL RELATIONSHIP Be - Al
Form amphoteric oxides
Form carbides contain C4-
Form covalent hydride and halides
In present of access OH ions, both form [Be(OH)4]2- & [Al(OH)4]2- (soluble)
Form structure based on linked tetrahedral
COMPOUNDS OF ALKALI EARTH METALS
oxides
hydroxide
hydride
carbonate
sulphate
halide