Question

what are the common physical and the chemical features of the alkali metals

Answer 1

physical properties :

all the alkali metals are silvery white soft and light metals because of the large size these metals have low density which increase down the group from Lithium to caesium however Potassium is lighter than sodium the melting and boiling points of the alkali metals are low indicating with metallic bonding due to the presence of the only single valence electron in them the alkali metals and their souls impart characteristic colour to an oxidizing flame this is because the heat from the flame exist the outermost orbital electron to the higher energy level when the excited electrons come back to the ground state there is emission of radiration that falls in the visible region

chemical properties :

=>reactivity towards air
=>reactivity towards water
=>reactivity towards halogens
=>solutions in liquid ammonia:
the alkali metals dissolve in liquid Ammonia giving deep blue solutions which are conducting in nature

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Answer 2

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$<b><i>$your answer !!

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$<b><i>$Melting and boiling point "-All these metals are soft and have low melting and boiling points as the alkali metals have only one valence electron per metal atom and therefore the energy binding the atoms is low .


Density :-the densities of the alkali metals are quite low as compared to the other metals Lithium ,sodium ,potassium are lighter than water. The densities increase on moving down the group However Potassium is much lighter than sodium.


Electropositive character :- all the alkali metals are strongly electropositive or metallic and the character the electropositive character of an element is expressed in the terms of tendency of its atom due to release electrons


Reactivity towards air or oxygen :- all the alkali metals get tarnished on exposure to air and moisture due to the formation of oxides and hydroxides or carbonate on their surfaces when heated in excess of our oxygen they burn and from different types of oxides depending upon the nature of metal.


Reactivity towards hydrogen :- all the alkali metals react with hydrogen about at the high temperature to form the hydrides which are ionic in the nature the stability of hydrides decreases from Lithium this is due to the fact that as size of alkali metal increases from Lithium and The Bond becomes weak.


Reactivity towards halogens :- the alkali metals readly combines with halogens to form ionic halides the reactivity of alkali metals towards a halogen increases on moving down the group this is due to decrease in ionization enthalpy or increase in electropositive character as we move down the group.