I/GCSE Chemistry Chapter Analysis - Chapter 2: Inorganic Chemistry - Alkali Metals
For I/GCSE Chemistry, you should know:
Alkali Metals:
The alkali metals are a group of highly reactive elements in the periodic table, consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These elements share similar properties and reactivity, which is why they are recognized as a family of elements.
Similarities in Reactions with Water:
One of the key pieces of evidence that supports the recognition of the alkali metals as a family is the similarities in their reactions with water. When an alkali metal is placed in water, it reacts vigorously, producing a basic solution and releasing hydrogen gas. The general reaction can be represented as:
2M(s) + 2H2O(l) → 2M+(aq) + 2OH-(aq) + H2(g)
where M represents the alkali metal. This reaction is consistent across the group, with the intensity of the reaction increasing as you move down the group. This trend in reactivity is a clear indication that the alkali metals share fundamental similarities in their chemical properties.
Differences in Reactions with Air and Water:
While the alkali metals share similarities in their reactions with water, there are also notable differences in their reactions with air and water. As you move down the group, the reactivity of the alkali metals increases. Lithium, the lightest alkali metal, is the least reactive, while francium, the heaviest, is the most reactive. This trend in reactivity can be observed in the differences in the reactions of these elements with air and water.
Lithium, for example, forms a thin oxide layer on its surface when exposed to air, which protects the metal from further reaction. In contrast, the heavier alkali metals, such as sodium and potassium, react violently with air, producing flames and sparks. Similarly, the intensity of the reaction with water increases as you move down the group, with the heavier alkali metals reacting more vigorously.
Trends in Group 1:
The trends in the properties and reactivity of the alkali metals can be explained by the electronic configurations of these elements. As you move down the group, the atomic radius of the alkali metals increases, and the valence electrons become more loosely held. This makes the valence electrons more readily available for chemical reactions, leading to the observed increase in reactivity.
Work hard for your I/GCSE Chemistry examination!
End of analysis. Great!
