1 - Inorganic Chemistry and the Periodic Table Flashcards
Atomic Radius trend in group 2?
Increases down the group as there are more shells of electrons.
Melting Point trend in group 2?
Melting points decrease down the group as the metallic bonding is weakened by the increased atomic radius as the distance between the positive ions and the delocalised ions increases and thus the electrostatic attractive force decreases in strength.
1st Ionisation energy trend in group 2?
Decreases down the group as the outermost electrons are successively further from the nucleus and are more shielded, leading to an increase in repulsive force from the electrons.
Reactivity trend in group 2?
Increases down the group as the atomic radii increases and there is more shielding. The attraction between the outermost electron and the nucleus is therefore decreased and it is easier to remove electrons and form cations.
Group 2 reactions with oxygen?
Burn in oxygen to form metal oxides (ionic bonding)
Group 2 reactions with chlorine?
Reacts with chlorine to form metal chlorides (MgCl2)
Group 2 reactions with water?
Increasing reactivity with water down the group, creating more vigorous bubbling of H2 down the group.
Mg will burn in steam to produce MgO and H2
In warm water it will make the hydroxide product Mg(OH)2 + H2
Other group 2s will form the hydroxide and hydrogen with cold water
Observations: Fizzing, metal dissolving, Solution heating up
Group 2 ionic oxide reactions with water?
Forms hydroxides, higher pHs down the group
Reaction of group 2 ionic oxides with acids?
Produces salt and water (MgCl2 + H2O)
Reaction of group 2 hydroxides with acids?
Produces salt and water (MgCl2 + H20)
Solubility trend of group 2 hydroxides?
- Increasingly soluble down the group
- Mg is sparingly soluble, forms Mg(OH)2, white precipitate, which is milk of magnesia, used as antacid (preferable as only weakly alkaline)
- Ca(OH)2 is limewater, used to detect for CO2 or neutralise acidic soil
Solubility trend of group 2 sulphates?
- Less soluble down the group
- BaSO4 used as a contrast medium in medical x-ray photographs
Group 2 decomposition trend?
- Decomposes into metal oxide and CO2
- The ease of thermal decomposition decreases down the group and thermal stability increases down the group
- Cations become bigger and have less of polarising power and distort the carbonate ion less. The C-O bond is weakened less and breaks less easily
Group 1 decomposition trend?
Lithium is the only element to decompose as it is such a small ion that it has a polarising effect
Experiment to investigate the ease of group 2 carbonate decomposition?
Heat known mass of carbonate and pass gas through limewater. Time for the first permanent cloudiness to appear.
Thermal decomposition trend of group 2 nitrates?
- Decompose to produce group 2 oxide, oxygen and nitrogen dioxide gas. Brown gas (NO2) would be observed.
2Mg(NO3)2 –> 2MgO + 4NO2 + O2 - The ease of thermal decomposition decreases down the group and thermal stability increases down the group.
- Cations become bigger and have less of polarising power and distort the carbonate ion less. The N-O bond is weakened less and breaks less easily
Thermal decomposition trend of group 1 nitrates?
- Produces Nitrate (III) salt + Oxygen 2NaNO3 --> 2NaNO2 + O2 Sodium nitrate(V) --> Sodium nitrate(II) - Exception: Lithium nitrate decomposes the same as group 2 nitrates: 4 LiNO3 --> 2Li2O + 4NO2 + O2
