TOPIC 4: Inorganic Chemistry And The Periodic Table Flashcards
(26 cards)
Ionisation energy trend - group 2
Decreases as atomic radius increases
Reaction with water - group 2
Form metal hydroxides (base)
X + 2H2O -> X(OH)2 + H2
Reactivity increases down the group
Be no reaction, Mg with steam (MgO instead)
Reaction with oxygen- group 2
Form metal oxides (base)
2X + O2 -> 2XO
Redox
All white solids
Reaction with chlorine - group 2
X + Cl2 -> XCl2
Redox
Oxides react with water (group 2)
Forms alkaline solution
XO + H2O -> X(OH)2
Hydroxide dissociates (OH- formed)
Down, alkalinity and solubility increase
MgO reacts slowly and hydroxide barely dissolves.
BeO no reaction, hydroxide is insoluble
Neutralisation - group 2
Acid + Base -> Salt + Water
XO + 2HCl -> XCl2 + H2O
X(OH)2 + 2HCl -> XCl2 + 2H2O
Solubility - group 2
Sulfates (SO4 2-) decreases down group
Hydroxides (OH -) increases down group
(If single charge increases down, if double decreases)
Thermal decomposition - group 2 compounds (carbonates and nitrates)
XCO3-> XO + CO2
2X(NO3)2 -> 2XO + 4NO2 + O2
Become more thermally stable (distort electron clouds less) as go down group as charge density decreases.
Thermal decomposition- group 1 compounds
Carbonates are thermally stable under Bunsen but
Li2CO3 -> Li2O + CO2
Except (LiNO3 -> Li2O + NO2 + O2)
2XNO3 -> 2XNO2 + O2
More thermally stable than group 2
Nitrate ion
Nitrite ion
NO3 -
NO2 -
Test thermal stability (NO3- and CO3-)
NO3 - time per O2 volume (syringe or relight glowing splint)
Specific amount of NO2 brown gas (toxic so fume cupboard)
CO3 2- time per CO2 (limewater cloudy or gas syringe)
Flame test (cations) why and how.
- Electrons absorb energy to move to higher levels, then drop and release as light of different wavelengths
- Dip nichrome wire in concentrated HCl, dip into sample and place wire in blue Bunsen flame to observe
Flame test: colours
Li Ca
Na Sr
K Ba
Rb
Cs
Red Brick-red
Orange Crimson
Lilac Green
Red
Blue
Halogens - group seven
F2 - pale yellow gas
Cl2 - pale green gas
Br2 - brown-orange liquid
I2 - grey solid
Halogens trends (3)
Boiling point: increases down group (greater London forces)
Electronegativity: decreases down
Reactivity: decreases down (smaller radius attracts electrons easier) and thus less oxidising
Displacement reactions - group 7
More reactive halogen displaces less reactive halide ion.
Halogen will dissolve readily in organic solvent, forming a layer above aqueous (colour)
Colour:
Water. Hexane
Cl colourless
Br yellow Orange
I brown Violet
Reactions - group 1 and 2 elements
With halogens to form metal halides
Disproportionation halogen reaction with cold alkalis
X2 + 2NaOH -> NaOX + NaX + H20
Disproportionation halogen reaction with hot alkalis
3X2 + 6NaOH -> NaXO3 + 5NaX + 3H2O
Bleach - disproportionation
2NaOH + Cl2 -> NaClO + NaCl + H20
- treat water, paper and fabric, clean agents
Water sterilisation - disproportionation
H20 + Cl2 -><- HCl + HClO
HClO + H2O -><- ClO- + H3O+
Chloric (I) acid ionises to make chlorate (I) ions (hypochlorite ions)
Reducing power of halide ions
Increases down group (as lose electron more readily)
Two tests:
Sulfuric acid and silver nitrate solution
Halide ions and concentrated sulfuric acid reduction
H2SO4
NaCl- only reaction to make NaHSO4 and HCl (white misty fumes)
NaBr- as Cl and redox to make SO2 and Br2 (orange vapour)
NaI- as Cl and Br and redox to make S (yellow solid) and I2 (purple vapour) and to make H2S (rotten egg smell toxic)
Hydrogen Halides and water and ammonia
Dissolve to form acidic solutions and air white misty fumes
HCl -> H+ + Cl-
HCl + H2O -> H3O+ + Cl-
Ammonium halides, white misty fumes
NH3 + HCl -> NH4Cl
