Reactivity Trends A1 Flashcards
Module 3
What kind of agents are group 2 elements? Why?
Reducing agents. They lose electrons (are oxidised) causing other elements to be reduced.
Properties of Group 2 elements:
Similar to metals:
- high m.p and b.p.
- good thermal and electrical conductors
What happens to reactivity as you go down group 2? Why?
Reactivity increases
1) increased atomic radius
2) increased electron shielding
3) So nuclear attraction to outer electrons is weaker.
Group 2 oxides act as ____ and react with water to form _______ and with acids to form ____.
bases
hydroxides
salts
The solubility of the group 2 hydroxides ______ down the group and as a result, so will ______.
increases
alkalinity
All group 2 carbonates will react with acids. They will also _________ ________ to form an oxide.
e.g.
thermally decompose
e.g. MCO3 + 2HCl –> MCl2 + H2O + CO2
MCO3 –> MO + CO3
Describe the uses of Group 2 compounds - give examples
Calcium Hydroxide used to neutralise acidic soils.
Magnesium hydroxide and calcium carbonate used in antacids (e.g. Rennie’s)
What is disproportionation?
When the same element is both oxidised and reduced in a reaction.
What is the oxidation number of an element in it’s natural state?
0
What is the sum of oxidation numbers in a molecule?
0
What is the normal oxidation number of Oxygen and what are the two exceptions?
-2
Peroxides (e.g. H2O2) where O is -1
and When combined with F it is +2 (e.g. O2F)
What is the exception to the halogen’s oxidation numbers being -1?
When bonded to oxygen or other halogens.
Why is using Chlorine in the process of cleaning water a problem?
It is toxic and it reacts with organic substances to form chloroalkanes which are carcinogenic.
Cl2 + 2NaOH —>
Cl2 + H2O —>
What type of reaction are these?
—> NaClO + NaCl + H2O
—> HClO + HCl
Disproportionation
Remember to explain USING OXIDATION NUMBERS
The b.p. of Halogens ________ as you go down the group. Why?
Increases - more electrons so stronger London forces
