Alkali Group

The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium(Rb), caesium (Cs), and francium (Fr). This group lies in the s-block of the periodic table as all alkali metals have their outermost electron in an s-orbital:this electron configuration results in their characteristic properties. The alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterized homologous behaviour.

The alkali metals have very similar properties: they are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen. Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free element. In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements,excluding hydrogen (H), which is nominally a group 1 element but not normally considered to be an alkali metal as it rarely exhibits behaviour comparable to that of the alkali metals. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.

What are the similar properties of alkali metals? 

Alkali metals share many similar properties including:

• They are shiny, soft, metals.
• They are very reactive.
• They all have one valence electron in the outermost shell which they seek to lose in order to have a full outer shell. This is what makes them so reactive.
• They are soft enough to be cut with a knife.
• When exposed to air, they tarnish due to oxidation.
• They are not found in nature as a free element, but generally as salts.
• They react when coming into contact with water. Some of them will even explode when they come into contact with water.
• They are malleable, ductile, and good conductors of electricity and heat.
• They have a low density when compared to other metals.

Order of Abundance 

The most abundant of the alkali metals on Earth is sodium. Here is the list in order:

1. Sodium
2. Potassium
3. Lithium
4. Rubidium
5. Cesium
6. Francium

Interesting Facts about Alkali Metals

• Because they are so reactive with air and water, they are generally stored in oil.
• Cesium and rubidium are used to make atomic clocks. Cesium clocks are considered the most accurate of all clocks.
• Sodium and potassium both play an important role in biological life on Earth. We cannot live without them.
• Sometimes cesium is also spelled "caesium."
• They like to form salts by combining with halogens.
• The name "alkali" is derived from the Arabic word for "ashes."
• Different alkali metals burn with different colored flames including sodium (orange yellow), lithium (red), potassium (lilac), rubidium (red), and cesium (blue or violet).
• All alkali metals have odd atomic numbers.
• They are considered to be more similar to each other than any other group in the periodic table.
• The compound ammonium has very similar properties to the heavier alkali metals.
• When moving down the periodic table, each alkali metal has an increasing atomic radius as well as increasing reactivity