Topic 4 - Inorganic Chemistry and Periodic Table
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How does the reactivity change down group 2?
increases
Why does the reactivity increase down group 2?
• more electrons/electron shells • outer electrons further from nucleus • weaker electrostatic attraction between nucleus and outer electrons • less energy required to remove electrons
How does the ionisation energy change down group 2?
decreases
Why does the ionisation energy decrease down group 2?
• more electrons/electron shells • outer electrons further from nucleus • weaker electrostatic attraction between nucleus and outer electrons • less energy required to remove electrons
How does the atomic radii change down group 2?
increases
Why does the atomic radii increase down group 2?
• more electrons - more electron shells
How does the solubility of sulphates change down group 2?
decrease
How does the solubility of hydroxides change down group 2?
increase
group 2 metal + oxygen ->
metal oxide white solid
group 2 metal + water -> liquid water
metal hydroxide + hydrogen
group 2 metal + water -> steam
metal oxide + hydrogen
group 2 metal + chlorine ->
metal chloride white solid
group 2 oxide + water ->
metal hydroxide
thermal decomposition of group 2 carbonates (and Li2CO3) carbonates ->
metal oxide + carbon dioxide
thermal decomposition of group 1 nitrates (except LiNO3) nitrate ->
metal oxide + nitrogen dioxide
What is thermal decomposition?
breaks down of a substance into two or more substances due to heat
What is thermal stability?
likelyhood of a substance to undergo a change at a particular temperature -how easily a substance breaks down under heat
thermal decomposition of group 1 nitrates (except Li2NO3) nitrate -> XNO3
group 1 nitrate + oxygen XNO2 +1/2 O2
thermal decomposition of group 2 nitrates nitrate -> X(NO3)2
metal oxide + nitrogen dioxide + oxygen XO + 2NO2 + 1/2 O2
How do group 1 and 2 nitrates and carbonates change in thermal stability down the group?
increase in thermal stability -require a higher temperature to thermally decompose
Describe the change in thermal stability down the group (1 or 2)
-ionic radii decreases (-more energy levels) -volume of ion increases -charge remains constant ∴ charge density decreases -have less of a polarising power on negative ions -cause less distortion of electron cloud -higher thermal stability
Describe the change in thermal stability across a period
• same period ∴ same number of energy levels • group further to right has more protons -greater nuclear charge so greater electrostatic attraction between nucleus and outer electrons • group 2 ions have higher charge and lower volume than group 1 ions ∴ higher charge density • cause more distortion of electron cloud of negative ion • lower thermal stability
What are the three aspects to Fajan’s rules that allow us to predict a compound’s distortion of electron density?
• high charge of cation (+ve ion) • small cation (+ve ion) • large anion (-ve ion)
What does a higher charge and smaller ionic radii result in?
• higher charge density • more distortion of electron density • less thermally stable