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Alkali Metals

February 6, 2013

Alkali Metals (chem)

Alkali Metals which are a group in the modern periodic table consisting of chemical elements Lithium
(Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs) and Francium (Fr). Most commonly they
are found in compounds form not in the elemental form.

In Periodic Table Alkali Metals are located in the first column or group 1A and are arranged in increasing
order of atomic number. These metals are placed in the s-block of periodic table as all alkali-metals have
their outer most electrons in s-orbital.

They form alkalis when they react with water since these types of metals are called as alkali-metals.
These metals are having only one electron in outer most shell, since they are ready to lose one electron
to other metal to form ionic boding. They provide the best example of group trends in properties in the
periodic table.

They do not occur freely in nature only found in salts and are very reactive metals especially the metals
like caesium and francium are highly reactive element in this group. Heavier alkali-metals are reacts
more vigorously with water than lower alkali-metals.

Alkali Metals Properties are common to other metallic element properties.

They are ready to react with non-metals, specifically halogens. They are ionic in nature, since they can
lose the valance electrons from its outer most orbital to form cations due to the lower ionization energy
and bigger atomic sizes.

Properties of Alkali Metals are,

-They can cut very easily because they are very soft and they have low melting and boiling point
-They are shiny compared with other metals.
They are highly reactive at standard temperature and pressure due to its low ionization energy;
hence they are stored under the oil to prevent reaction with air.
-They are malleable and ductile as with all metals.
-They conduct heat and electricity, since they are good conductor.
-They are explode when these metals are exposed to water.
-It has lower density compared with other metals.
-It has low electro negativity.
-In its periods, it has largest atomic radii.
– It has very high lattice energy, due to its stringer electrostatic forces.
– They are very strongly electropositive or metallic in character.

Alkali-Metals are reacts vigorously with Water to make their respective hydroxides and hydrogen with

Those hydroxides are strongly alkaline in nature.
The reaction of alkali metals in water is exothermic reaction, since it produces heat energy during the
reaction. It reacts with water to form alkaline hydroxides which are strongly alkaline in nature, so that it
should be handled with care.
Heavy alkali-metals are reacting with water more vigorously than the lighter one. For example caesium
produces larger explosion then sodium when dropped in water.

Alkali metal + water ————-> Alkali hydroxide + hydrogen

M + H2O ———–> MOH + 1/2 H2


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