4: Inorganic Chemistry Flashcards
Trend in ionisation energies down group 2
Ionisation energies decrease
Reason for group 2 trend in ionisation energies
The atomic radius increases and the shielding increases
Trend in reactivity down group 2
Metals become more reactive down group 2
Combustion of group 2 metals (excluding barium)
2M + O2 → 2MO
Combustion of barium
Ba + O2 → BaO2
Reaction of group 2 metals with water (except magnesium and beryllium)
M + 2 H2O → M(OH)2 + H2
Reaction of magnesium and steam
Mg + H2O → MgO + H2
Reaction of metals and chlorine
M + Cl2 → MCl2
Reaction of group 2 metal oxides with water (excluding beryllium oxide)
MO + H20 → M(OH)2
General reaction of acid and base
Acid + Base → Salt + Water
Trend in solubility of group 2 sulphates
Solubility decreases down the group
Group 2 sulphates with their solubility
Magnesium - Soluble
Calcium - Slightly soluble
Strontium - Insoluble
Barium - Insoluble
Trend in solubility of group 2 hydroxides
Solubility increases down the group
Group 2 hydroxides with their solubility
Magnesium - Insoluble
Calcium - Soluble
Strontium - Soluble
Barium - Soluble
Trend in thermal stability of carbonates
Thermal stability increases down the groups
Reason for trend in thermal stability of carbonates
- As the cations become larger, the charge density becomes less, so they distort the anion less
- This distortion weakens the C-O bond
Reason for group 1 carbonates being more stable than group 2
The charge on the cation is less
Nitrate thermal stability
-All nitrates thermally decompose
Group 1 nitrates thermal decomposition (excluding lithium nitrate)
2 MNO3 → 2 MNO2 + O2
Group 2 nitrates thermal decomposition
2 M(NO3)2 → 2 MO + 4 NO2 + O2
Lithium nitrate thermal decomposition
4 LiNO3 → 2 Li2O + 4NO2 + O2
Explanation of flame colours in flame tests
- When group 1 or 2 metals or their compounds are placed in a flame, the electrons are pushed to a higher energy level
- As the electrons drop back down they give out energy as light
How to show the trend of thermal decomposition in carbonates
- Pass the gas produced through limewater
- Record how long it takes to turn cloudy
Appearance of Fluorine
RTP - yellow gas
Appearance of Chlorine
RTP - pale green gas
Aq - colourless
Org - colourless
Appearance of Bromine
RTP - brown liquid
Aq - yellow/orange
Org - orange
Appearance of Iodine
RTP - grey solid
Aq - brown
Org - Purple
Trend in MP/BP of halogens
MP/BP increase down the group as there are more electrons, and therefore stronger London forces
Trend in electronegativity of halogens
Electronegativity decreases down the group and atomic radius increases and more shielding
Trend in reactivity of halogens
Reactivity decreases down the group as the attraction of the nucleus decreases as there is more shielding
How to show trend in reactivity in halogens
Can be shown by the displacement in the reaction of a halogen with a Group 1 metal halide (e.g Cl2 + 2KBr → Br2 + 2KCl)
Reaction of a halogen with a metal
2 M + X2 → 2 MX
Chlorine reaction with water
Cl2 + H20 ⇌ HCl + HClO
Use of reacting chlorine with water
HClO sterilises water, and is in small quantities as the reaction is reversible
Chlorine reaction with cold NaOH
Cl2 + NaOH → NaClO + NaCl
Chlorine reaction with hot NaOH
3 Cl2 + 6 NaOH → NaClO3 + 5 NaCl
Formula of bleach
NaClO
Reaction of Fe(II) with halides
Fluorine, Chlorine and Bromine are strong enough to oxidise F2 + 2 Fe(II) → 2 F- + 2 Fe(III)
Reaction of Group 1 halides with concentrated sulphuric acid
MX + H2SO4 → MHSO4 + HX
Addition reaction following Group 1 halides reaction with conc. H2SO4
Only with bromide/iodide: 2 HX + H2SO4 → X2 + 2 H20 + SO2
Trend in strength as reducing agent in halides
As the halide ions become bigger they become more able to lose an electron and therefore become stronger
Dissolving and dissociation of hydrogen halides in water
HX → H+ + X-
Reaction of hydrogen halides and gaseous ammonia
HX + NH3 → NH4X
Observation in reaction of hydrogen halides and gaseous ammonia
Dense white smoke produced
