Science and Technology for UPSC Examinations [Chemistry] Part 9- Notes on Alkali metals

May 22, 2013 May 22, 2013

This family is Group 1 of the periodic table and includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).

Hydrogen is a nominal member because it rarely shows any similar property. So Hydrogen is not among the alkali metals.
Alkali metals are all highly reactive and are never found in elemental forms in nature.
They are usually stored immersed in mineral oil or kerosene (paraffin oil) because of their high reactive nature.
They have low melting points and densities.
All alkali metals have silver color except caesium which has a golden color.
the react with halogens and make salts for example NaCl (table salt)
They react with water and make Hydroxides for example NaOH
Potassium and rubidium are naturally weakly radioactive elements and they each contain a long half-life radioactive isotope.
Under standard conditions Lithium is the lightest metal and the least dense solid element.
Lithium carbonate is used in use in psychiatry
Organolithiums are also used in polymer synthesis and for creating carbon-carbon polymers.
Lithium batteries are disposable (primary) batteries with lithium metal or lithium compounds as an anode, while the Lithium ion batteries are high energy-density rechargeable batteries.
Al-Li alloys are used in aeronautics.
The sodium vapor lamp uses sodium in an excited state to produce light.
Alkali metal as the Na+ ion is vital to animal life.
Molten sodium is used as a coolant in some types of nuclear reactors.
It decreases in blood pressure and decreases in sodium concentration sensed within the kidney result in the production of rennin which in turn helps in secretion of ant diuretic hormones
Animal cells, potassium ions are vital to cell function. They participate in the Na-K pump and in helping to restore the body’s total amount of fluid.
Sodium is the chief cation in fluid residing outside cells in the mammalian body
Low sodium intake may lead to sodium deficiency which is known as hyponatremia.
About 93% of the world potassium production is consumed by the fertilizer industry
Potassium chloride is used in execution by lethal injection.
Potassium vapor is used in several types of magnetometers
Caesium is one among the five metals which are liquid at room temperature. These are Mercury (melting point −39 °C), Francium (27 °C) caesium (28 °C), Gallium (30 °C) & rubidium (39 °C)
Caesium has been used in the petroleum Industry exploration as caesium formate.
The caesium atomic clocks use the resonant vibration frequency of caesium-133 atoms as a reference point. Precise caesium clocks measure frequency with an accuracy of from 2 to 3 parts in 1014, which would correspond to a time measurement accuracy of 2 nanoseconds per day, or one second in 1.4 million years.