This document discusses the physical and chemical properties of Group II elements. It outlines trends in properties like atomic radii, ionization energy, melting point, and boiling point across the group. These trends are explained by factors like effective nuclear charge and structure/bonding. Chemically, Group II metals are strong reducing agents, with reactivity and reducing ability increasing down the group. Common reactions outlined include reaction with oxygen and water, and thermal decomposition reactions. Exceptions and important reactions are highlighted.

1. Group II

2. Group II
The focus for Inorganic Chemistry (Gp II, VII, Transition
Elements) is the trends for the physical and
chemical properties of the elements.

3. Physical Properties
•
•
•
Atomic radii
Ionisation Energy (IE)
Melting point/ boiling point (mp/ bp)
For each property, it is important to:
(1) remember the trends
(2) learn to explain for the trends

4. Physical Properties
The key to explaining correctly for the trends is to remember
the factors that affect each trend.

5. Physical Properties
Property
Factor
atomic/ ionic radii, IE,
electro-vity
effective nuclear charge
(nuclear charge + screening
effect)
mp/bp, ∆Hfusion/∆Hvaporisation,
conductivity, solubility
structure & bonding (lattice
energy)
ease of decomposition,
decomposition T
polarising power of cation

6. Chemical Properties
- Gp II metals are strong reducing agents
Down the group
- Tendency to be oxidised ↑
- Reducing ability ↑
- Reactivity ↑

7. Chemical Properties
1. Rxn with Oxygen
M (s) + O2 (g) 2MO (s)
2. Rxn with Water
M (s) + H2O (l)  M(OH)2 (aq) + H2 (g)
Exception: Mg (s) + H2O (g)  MgO (s) + H2 (g)
3. Rxn of Oxides with Water
MO (s) + H2O (aq)  M(OH)2 (aq)

8. Chemical Properties
4. Thermal Decomposition
M(NO3)2
(s)
→ MO(s) + 2NO2(g) + ½O2(g)
MCO3 (s)
→ MO(s) + CO2(g)
M(OH)2
(s)
→ MO(s) + H2O(g)
Down the group, thermal stability ↑
It is important to memorise the general eqns!

9. Physical Properties
• Students often mix up the explanation for trends for
melting point and decomposition temperatures.
• For ionic compounds, melting involves breaking of
‘intermolecular’ bonds while decomposition involves
breaking ‘intramolecular’ bonds.

10. Chemical Properties
M2+
Decomposition
breaks covalent bonds
∞ strength of covalent bond
∞ polarising power of M
Melting
breaks ionic bonds
∞ strength of ionic bond
∞ q + q–
r+ + r–

11. Solubility Trends
Solubility of Gp II…
- carbonates/ sulfates decrease down Gp
- hydroxides/ oxides increase down Gp
•
•
For solubility trends, you only need to memorise the
trends.
The explanation for the trends is not straightforward
and unlikely to be tested.

12. Further Reading
Q: How can we experimentally determine the trend for the
ease of decomposition of Gp II compounds?

13. Further Reading
A: There are a few methods:
-
-
Measure volume of gas collected after a fixed time
i.e. the larger the volume of gas produced, the easier
the compound decomposes.
Measure the time taken to collect a fixed volume of
gas
i.e. the shorter the time taken, the easier the
compound decomposes