The Group 2 Elements
The elements in Group 2 all have hydroxides that are alkaline, which is reflected in the common name for this group: the alkaline earth metals.

Physical Properties
The Group 2 elements have the following general properties:

they have reasonably high melting and boiling points
light metals with low densities
form colourless compounds

Electronic Configuration
The elements in Group 2 have their highest energy electrons in an s-sub shell. Together with Group 1 they form the s-block of the Periodic Table.
Each Group 2 element has:

two electrons more than the electronic configuration of a noble gas
an outer shell containing two electrons

Reactivity of Group 2 Elements
The Group 2 elements are reactive metals and strong reducing agents.
Group 2 elements are oxidised in reactions.

Each atom loses two electrons from its outer s sub-shell to form a 2+ ion: M ---> M2+ +2e-
Reactivity increases down the group, reflecting the increasing ease of losing electrons
The decrease in ionisation energies down Group 2 is an important factor in this process.

Reaction with Oxygen
The Group 2 elements react vigorously with oxygen.

this is a redox reaction
the product is an ionic oxide with the general formula MO

Calcium reacts with oxygen to form calcium oxide.
2Ca + O2 ---> 2CaO
By applying oxidation numbers to this reaction, you can identify the oxidation and reduction processes.
0       0         +2 -2
0        0         +2 -2
Calcium is oxidised and oxygen is reduced.

Reaction with Water
The Group 2 elements react with water to form hyroides with the general formula M(OH)2. Hydrogen gas is also formed.
Ca + 2H2O ---> Ca(OH)2 + H2
0    +1            +2             0
       +1                              0

only one H atom from each H2O has been reduced
the other H atom does not change its oxidation number

Mg reacts very slowly with water. As you move further down the group, each metal reacts more vigorously with water.

	Criado por siobhan.quirk mais de 11 anos atrás

Undergraduate Chemistry - Part 1 (The Periodic Table) Notas sobre Group 2 Elements: Redox Reactions, criado por siobhan.quirk em 20-05-2013.