Alkali metals are a set of six elements that together make up the group 1 of periodic table. In fact the only element in group 1 that is not an alkali metal is hydrogen. Alkali metals are all located in the first column of the periodic table. Members of this group are sodium, lithium, potassium, rubidium, cesium and francium. Alkali metals are found in nature as salts and not as free elements. The most abundantly found element of the group is sodium, which is followed by potassium, lithium, rubidium, cesium and francium, in that order.
Alkali metals are all soft and can be cut even with a knife. They are all shiny and have a single valence electron in the outer shell. All of them are seeking to lose this single electron to have a complete shell which is why they are very reactive. While alkali metals are tarnished when exposed to air as a result of oxidation, they react when they come in contact with water. Some alkali metals even explode when they are brought in contact with waters. Cesium and francium are the two most reactive elements of the group. Alkali metals also have characteristically lower density, compared to other metals. They are also good conductors of electricity.
Alkali metals are widely used in various fields. Some of their more common uses are as follows:
Lithium (glass/ceramic production, electrical batteries, electronics, lubricating greases, pyrotechnics, optics, nuclear industry and medicine production).
Sodium (anti-scaling, as an alloying metal, to manufacture several compounds such as sodium chloride and sodium hydroxide).
Potassium (fertilizers, food nutrient, industrial usage as a neutralizing agent and in laboratory as a heat transfer medium and for reactive distillation).
Cesium (as a drilling fluid in extractive oil industry, atomic clocks, electronics, as centrifugation fluids in molecular biology, chemical use, medical use and as a propellant in ion engines).
Rubidium (fireworks, atomic clocks, thermoelectric generation, as a photocell component, medicine and nuclear medicine).
Francium (the instability and rarity of francium means it has no commercial application. It is however, used for research purposes in the field of chemistry).
Listed below are some very interesting and rarely known facts about alkali metals:
- Owing to the highly reactive nature of alkali metals, they are stored in oil.
- The name ‘alkali’ is of Arabic origin and means ‘ashes’.
- Alkali metals are never found as free elements in nature and are exclusively found in salts.
- Rubidium and Cesium atomic clocks are the best known applications of these alkali elements and cesium atomic clock is especially considered the most accurate.
Sodium and Potassium are included in the list of ten Most Common Elements in Earth’s Crust. While sodium with 2.6% of earth’s crust is ranked 6th, potassium is the 7th most common element with a share of 1.5%
- Alkali metals present the best example of group trends in the periodic table and are more similar to each other than any other group.
- Sodium and Potassium are also two major nutrients. They are absolutely essential for life to exist. Sodium regulates blood volume, blood pressure and osmotic equilibrium. An average 500 milligrams of sodium is physiologically required every day.
- Alkali metals have different colored flames when burnt. They are sodium (orange/yellow), lithium (red), potassium (lilac), rubidium (red) and cesium (purple/blue).
- Alkali metals are more reactive and have more atomic radius as we move down the table. Francium is the most reactive member of the group.
- While sodium and potassium are almost equally abundant in earth’s crust, sodium is much more commonly found in ocean than potassium.
- Large quantities of potassium are found in Russia, Belarus, Germany, Jordan, Canada and United States.
- Lithium’s name is derived from the Greek word ‘lithos’, which means stone. It is named as such because it was discovered from a mineral source unlike sodium and potassium which were discovered from plant sources.
- Prolonged sweating results in loss of sodium ion from the body, which must be replaced through diet.