A2 Periodicity Flashcards
Oxides with water
Solutions of the oxides of the elements in period 3 go from alkaline to acidic across the period
1)Na2o contains o2- ions which is a very strong base readily produces oh- very alkaline
2)Mgo also has o2- ions but less soluble so less alkaline solution produced
Aluminium oxide
-ionic and also covalent
-small Electronegativity differences between al and o
-also al is a small ion with high charge so it can get close to the oxide ion and distorts the oxide charge cloud
-aluminium metal is protected from corrosion in moist air by a thin layer impermeable to air and water
-it’s amphoteric
Oxides with water
Al2o3- ionic but bonding is too strong to separate ions partly because it has additional covalent binding
Silicon dioxide -giant macromolecules water doesn’t affect this structure acidic in nature
Phosphorus and surfer oxides are covalent and react with water to form acid solution
Na to mg
Soluble and ionic
Aluminium to silicon
Ionic amd covalent
Insoluble
Oxacid
Compounds
Strong acid
Disassociated fully in water
Acidic hydrogens are attached directly to o2
Wheee there at least one oxygen with a hydrogen is attached to a non-metal or early transition metal which makes an oxaxid
Has tetrahedral structure (109.5)
Phosphorus
Sulphuric acid
Oxanion
When oxacids lose their hydrogens becomes an anion
Called a conjugate base which is when a proton is removed from an acid
Eg.phosphate ion
Oxygen distribution evenly and all bond lengths the same
Delocalisation
When electrons spread out equally over all 4 bonds
Oxides of water general trend
Solutions of all the oxides of elements in period 3 go from alkaline to acidic across the period
Na2o
Mgo
Al2o3
Sio2
P4o10
Na2o
More alkaline so more soluble
Contains o2- which is strong base so attracts protons
Readily produces oh- which is very alkaline
Mgo
Also has o2- but less soluble so less alkaline solution produced
Aluminium oxide
Amphotenic
Ionic but also partially covalent
Small Electronegativity difference between al and o
Also al is a small ion with high charge so it can get close to the oxide ion and distorts the oxide charge cloud
Alumium metal is protected from corrosion in moist air by a thin layer of Al2o3
Insolubility in water impermeable to air and water
Ionic but binding is too strong to seperste ions
Sio2
Giant macro- water doesn’t affect this structure
P4o10 so2 so3
Simple covalent thus reacts with water
From acid solutions
Alumium oxide and acid -hcl
Salt and water formed
Al2o3+6hcl=2alcl3+3h2o
