Alkali Metals

Anyone preparing for JEE mains should have a deep understanding of elements on the periodic table. Alkali metals aren’t rare; in fact, there are a few that are among the most commonly used. They are also incredibly reactive, having unique properties for metals and it is important for any science enthusiast to know about their physical and chemical properties. If you’re wondering what alkali metals are, their major physical and chemical properties, and their uses, then keep on reading this blog as it contains everything you need to know about alkali metals. So let us quickly begin with the introduction of Alkali metals!

Introduction to Alkali metals

The alkali metals are a chemical group in the periodic table consisting of the chemical elements Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs), and Francium (Fr). Alkali metals are placed in group 1A of the periodic table and together with Alkaline earth metals, they form the s-block in the periodic table. Alkali metals are all shiny, highly reactive metals at standard temperature and pressure, and can all be cut easily with a knife. All the discovered alkali metals occur in nature, although francium is extremely rare and only occurs as a product of nuclear decay. As their name implies, alkali metals are highly reactive elements with a strong affinity for oxygen. They have an oxidation number of +1, which means that they lose one electron per atom to form positively charged ions (cations).

Major Physical and Chemical properties of Alkali metals

Alkali metals are soft and highly reactive elements. These metals are usually found in the +1 oxidation state. Due to their high reactivity, they rarely occur in their metallic form. Most of them exist in ionic compounds due to which they act as strong electrolytes. However, all the studies are based on the first five elements only since Francium is radioactive in nature and not much study is done in its regard. Below are some major physical and chemical properties of alkali metals:

Physical properties

The alkali metals are highly reactive, soft and are silvery-white transition metal elements found in group 1 of the periodic table. One of the most promising physical properties of Alkali metals is that they can be easily cut with a knife. In addition to this, Alkali metals have low density, melting points, and boiling points. Also, Lithium is the lightest metal in the whole periodic table. Similarly, Alkali metals also have a low heat of vaporization and sublimation. Other physical properties of Alkali metals include silver-like lustre and high ductility. Furthermore, Alkali metals are excellent conductors of heat and electricity thus they form good electrolytes. Summary of Alkali metals physical properties:

• Soft and shiny, have a silver-like luster
• Can be cut with a knife
• Low boiling and melting points
• Low heat of vaporization and sublimation
• Low density
• Good thermal and electrical conductivity

So, this was all about the physical properties of the Alkali metals now let us see some of their major chemical properties.

Chemical properties

The chemical properties of the alkali metals make them generally reactive and corrosive. Yet, they are all solid at room temperature, and most of them possess a crystalline structure. These metals are highly reactive and therefore do not occur freely in nature. They react violently with water and air, burn to form caustic basic solutions. Lithium and sodium have many common reactions. Both react vigorously with water to produce flammable hydrogen gas and caustic soda solutions. With oxygen, they burn with a brilliant white flame to form the peroxides and superoxides, e.g. Lithium peroxide (Li₂O₂) and Sodium peroxide (Na₂O₂), both of which decompose rapidly in water, liberating heat. Their high reactivity is explained by their tendency to lose their single valence electron, which is easily obtained due to the low ionization energy of group 1 elements as well as their generally lower melting and boiling points because they have smaller atomic radii. Summary of chemical properties of Alkali earth metals:

• Electronic configuration of ns1
• Low ionization energy that increases down the group
• Highly reactive due to one electron in the outermost shell
• +1 oxidation state
• React vigorously with water to form caustic solutions and release Hydrogen gas
• React with halogens to form alkali metal halides

Uses of Alkali metals

• Alkali metals react with water to form strong bases, as reflected by their naming: alkalis. These elements also react vigorously with oxygen and some halogens to form oxides and oxyacids
• The alkali metals all have a single valence electron in the outermost s-orbital that can  easily be removed. This allows them to easily form chemical compounds. Their high reactivity can be used to produce electricity or to extract other elements from ores or salts
• These metals are strong reducing agents and therefore can be used to produce hydrogen gas by reacting with acids or bases
• They perform a major role in the medicine and agricultural industry as well as in many manufacturing processes
• Potassium is widely used in making fireworks and Sodium metal is used as a coolant in nuclear reactor plants
• Similarly, sodium vapour is also used in street lights and Sodium lamps as it produces very bright and distinct yellow light

Conclusion

The alkali metal group lies in the s-block of the periodic table and is the first group in the second period. The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electrons 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 the air due to oxidation. Furthermore, alkali metals are highly reactive due to their low ionization energy and a single electron in the valence shell. They react vigorously with water and halogens. Alkali metals are commonly used in almost all industrial sectors. For example, it is widely used in nuclear power plants, in the extraction of ores, and in the pharma and agricultural industry.