Alkali metals or Group 1A elements belong to a common group due to its ns1 valence electronic configuration. The properties of an element have periodic dependence on its atomic number but not on atomic weight. These are similar to Group 17 (Halogens) in a way that, it attains noble gas configuration after losing its valence electron. That is why hydrogen is placed separately in the periodic table. Alkali elements belong to s-block, including hydrogen.
- These metals are soft, shiny, silvery white elements.
- They are highly reactive with water. They are mostly not found in free nature as they react quickly and vigorously. Some of these metals are stored in kerosene or other mineral oils.
- They oxidize rapidly in air. Due to oxide coating, its bright, shiny luster is hidden. When the coating is cut off with a knife, the shiny metal will be clearly visible.
- Luminant, colorful flame is produced by them when burned with oxygen.
- These have low ionization enthalpy (heat evolved when an atom gets ionized).
- These are strong reducing agents.
- They are malleable and ductile.
- Softness of the element down the group increases due to increasing atomic number because the metallic bond will decrease with increase in atomic size.
- The ionization energy of group 1A elements decreases down the group.
- These are good conductors of heat and electricity.
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Lithium is the lightest metal discovered yet. It is the only metal that reacts with nitrogen. Lithium Oxide is Amphoteric (both acid and base characteristics). Except Lithium, other alkali elements are predominantly ionic. The charge density on Lithium is stronger than other alkali metals due to which it is extensively hydrated. Lithium was discovered in 1817 by Johan Arfvedson, during petalite LiAlSi4O10 analysis. The word Lithium is derived from the Greek word 'lithos' meaning stone. Lithium is found in number of pegmatitic minerals, clays, brines, oceans, and in all living things.
Uses of Lithium
- Lithium is used in heat resistive ceramics and glasses.
- Alloy of Lithium is used in aircraft building.
- Lithium Deuteride is used as fusion fuel in thermonuclear weapons.
- Lithium batteries are packed with lot of energy as compared to other metals. Revolutionized devices like cell phones, computers use lithium batteries.
- Lithium salts are used as mood stabilizing drug.
- Lithium-6 is a main source for tritium production.
- Lithium is used in deoxidizing copper and copper alloys.
- Lithium compounds are used as pyrotechnic colorants in fireworks that produces red luminance.
- Lubricating greases are produced from Lithium.
Sodium is a chemical substance which we consume everyday in our food in the form of sodium chloride (common salt). Sodium is produced by electrolysis of sodium chloride. Sodium element is highly reactive. In 1806, Sir Humphry Davy, a chemist, obtained sodium by passing electric current through molten sodium hydroxide. Sodium was first produced through nuclear fusion in stars, by fusion of two carbon atoms. It can also be produced in stars when neon atoms gain a proton.
Uses of Sodium
- Sodium is used as luster in metals.
- Liquid Sodium is used as coolant in Nuclear reactors.
- Sodium salt of fatty acids are used in soap.
- NaK, an alloy of sodium and potassium, is an important heat transfer agent.
- Sodium compounds are used in paper, textile, petroleum and chemical industries.
- Sodium Iodide is used to treat extensive ringworm.
- Sodium is used in street lights and sodium vapor lamps as it can give yellow glow with bright luminance.
- Sodium hydroxide is used as oven cleaner.
Potassium is the 19th element in the periodic table. Potassium plays a vital role in the proper functioning of our body. It is an essential mineral that should be maintained in organisms. If potassium level is not balanced it may lead to hyperkalemia or hypokalemia. Potassium turns gray on exposure to air. To prevent oxidation and to keep out moisture, potassium is stored in petroleum.
Uses of Potassium
- Potassium chloride is essential for the growth of plants. It is used in fertilizers.
- Potash improves water retention, yield, nutrient value, taste, color, texture and disease resistance of food crops.
- Potassium chlorate and potassium nitrate are used in explosives and fireworks.
- Potassium nitrate is used as a food preservative.
- Potassium maintains blood pressure and acidity levels in our body.
- Potassium chromate is used in the tanning of leather and in the manufacture of inks, gun powder, dyes, safety matches etc.,
- Potassium is essential for normal cell respiration and electrolyte function as 95% of our cells are made of potassium.
- Potassium hydroxide is used to make detergents.
- Potassium helps to pump fluids inside the heart and the nerves.
Rubidium is a radioactive element. It is derived from a latin word rubius meaning deepest red.
Uses of Rubidium
- Rubidium 82 is used in myocardial perfusion.
- Rubidium is used in the manufacture of atomic clocks, electronic tubes, photocells.
- Rubidium is used as working fluid in vapor turbines.
- It is used as a component in the engines of space vehicles.
- Rubidium vapor is used in laser cooling.
- Rubidium chloride is used to induce cells to take up DNA.
- It is used in thermoelectric generators.
- Rubidium Carbonate is used in making optical glasses.
- Due to hyperfine structure of rubidium's energy levels, it is used in atomic clocks.
- A compound made up of rubidium, silver and iodine, has certain electrical characteristics and is used in making thin film batteries.
Cesium is an active metal. Chemically, cesium is the most electropositive element and combines with anions to form compounds. It is a highly toxic element. Cesium hydroxide is the strongest base discovered yet. It has many isotopes of which cesium-133 is a stable isotope and the most important standard for measurement of time (Cesium clocks or atomic clocks). Cesium is liquid at or near room temperature.
Uses of Cesium
- Cesium-134 is used in nuclear power industry.
- Used in photoelectric cells due to its quick electron emission.
- Cesium is used as catalyst for hydrogenation of certain organic compounds.
- It is used in propulsion systems.
- It removes air traces from vacuum tubes.
- Cesium is used in photovoltaic cells, television image devices, night-vision equipment.
- Cesium vapor is used in magnetometer.
- Cesium-137 is used in brachytherapy to treat cancers. (Brachytherapy is a cancer treatment method using radioactive elements)
- Cesium chloride solution is used in molecular biology for density gradient ultracentrifugation, primarily for the isolation of viral particles, subcellular organelles and fractions, and nucleic acids from biological samples.
- Cesium is used as a standard in spectrophotometry
- It is used in military aircraft.
Francium has the lowest electronegativity among all the known elements. It is a highly radioactive metal and heaviest of these metals. Francium is produced by bombarding thorium with protons or by bombarding radium with neutrons. This element is rare and is not used much. It is mainly used for scientific research in laboratory. It decays quickly as it has short half life.
Alkali metals are of great use to us but should not be used without expert guidance as they get violent during reactions and should be handled cautiously as they are toxic.