Compounds of Alkali Metals

Compounds of Alkali Metals

Alkali metals are also known as Group 1 or IA-group elements of the periodic table. They have been analysed and extensively researched worldwide over the past two centuries. These compounds share similar chemical and physical properties that vary as we move down the group. Furthermore, they are among the most reactive elements of the periodic table and have various applications. 

Introduction to Alkali metals and Compounds of Alkali Metals

Alkali metals are chemical elements and are placed in Group 1 of the periodic table. The alkali metals comprise sodium, lithium, potassium, caesium, rubidium, and francium elements. All alkali metals have an electronic configuration of ns1 (one electron in s-subshell) and are placed in the s block of the periodic table.

Alkali metals are soft silvery white-coloured metals that tarnish quickly in the presence of air. They all have one valence shell electron in their outermost shell and are highly reactive. They react with water to produce hydrogen gas and form caustic alkali solutions.

Beyond their reactivity, they possess several common properties. All are solids at room temperature and standard pressure; however, they have very low melting and boiling points.

The alkali metals have been known for thousands of years. They were initially used to make soaps. Later, these metals were used to make glass, ceramic tiles, and porcelain. Alkali metals have been used to make soft drinks and photographic films. Lithium is also used to make aluminium alloys and has been used on long missions in space.

Physical Properties of Alkali Metals

There are various physical properties of alkali metals that differentiate them from other periodic table elements. For example, all alkali metals are soft and have a silver-like lustre that is easily tarnished when they contact air. Another promising feature of these elements is that they are soft enough and can be cut with knives.

Other physical properties include low melting and boiling points, the heat of vaporisation, and sublimation. In addition to this, alkali metals also have low densities and are ductile in nature. Being metals, they are good conductors of electricity and heat. 

These elements are known for their softness and reactivity. Liquid sodium is used in car engines for cooling. Potassium is important in maintaining a regular heart rhythm. Lithium is used in batteries and medical treatments for manic depression. Caesium is used to reduce muscle spasms that occur during convulsions.

Trends in physical properties

These trends in physical properties become more pronounced down the periodic table, specifically for alkali metals, because the outermost shell electrons are more loosely bound than those of the transition metals. The outermost electrons are not shared with other atoms; hence, their properties will be affected by their increased ionisation energy and weaker metallic bonds.

The physical properties of alkali metals are characterised by their high reactivity. Thus, these elements cannot be stored in a pure form and must be stored as compounds. Several alkali metals occur in nature as carbonates, oxides, or sulphates.

Chemical Properties of Alkali Metals

All alkali metals are highly reactive because they readily lose their outer electron to form positive ions with a strong attraction to other atoms, a process known as oxidation. Sodium metal reacts instantly with water or even moisture in the air to form hydrogen gas and sodium hydroxide. This reaction is so fast that it ignites when exposed to air and explodes when it comes into contact with water or moist air.

All alkali metals have high thermal conductivity, reflecting their tendency to lose their outer shell electrons and form ions with an electropositive nucleus. Other chemical properties of alkali metals include low ionisation energy and an oxidation state of +1, indicating that alkali metals lose their outer shell electron to form positively charged ions (cations) with a +1 charge. Alkali metals also readily react with halogens to form alkali metal halides.

Sodium and potassium are highly reactive. Rubidium and caesium oxidise significantly when submerged in water or moist air. Francium only reacts with oxygen when it is inside an inert argon matrix. Alkali metals are never found in pure form in nature due to their reactivity. Instead they occur naturally only as compounds with other elements.  

Conclusion

Alkali metals are placed in Group 1 of the periodic table. They are highly reactive, soft, and silvery solids at room temperatures, although they often have a bright, silvery-white lustre. The alkali metals include sodium (Na), lithium (Li), caesium (Cs), potassium (K), rubidium (Rb), and francium (Fr).

They are all shiny, soft, highly reactive metals. They react with water, producing hydrogen gas. The reactive nature of the alkali metals is due to the presence of a single electron in their outer shell. These metals must be stored under oil or in mineral oil. The alkali metals’ distinct physical and chemical properties make them a key element in various industrial sectors, including pharma and agriculture.