Topic 4 - Inorganic Chemistry and Periodic Table Flashcards
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