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Element Encyclopedia
Just For Fun
The Alkali Metals
The alkali metals, found in group 1 of the periodic table, are very reactive metals that do not occur freely in nature. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements.
Physical Properties of Alkali Metals
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they have low melting and boiling points compared to most other metals
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they are very soft and can be cut easily with a knife
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they have low densities (lithium, sodium and potassium will float on water)
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they react quickly with water, producing hydroxides and hydrogen gas
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their hydroxides and oxides dissolve in water to form alkaline solutions
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they all have one valence electron
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Trends in Reactivity & Boiling/Melting Points
As you go down the group...
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their melting points decrease
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their densities increase
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they become softer
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they become more reactive
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The alkali metals are the most reactive metals.
They react with water to create hydrogen and an alkaline solution -
metal hydroxide
The alkali metals get more reactive as you go down the group because;
when alkali metals react with a non-metal, it gives away it's only electron in it's outer shell. As you go down the group, the elements have more electron shells, this makes the attraction between the valence electron and the nucleus less if they're farther apart, so it is easier to let go of the valence electron to react.
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Ion Formation
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Alkali metals tend to lose one electron and form ions with a single positive charge. They form ionic compounds (salts) in reaction with the halogens (alkali halides).
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The alkali metals react best with halogens.
The halogens have seven valence electrons, so they react well with
each other because the alkali metal gives it's valence electron to
the halogen, so they both end with eight valence electrons
- achieving stability
The alkali metal loses an electron, the halogen gains one electron.
Electrons are negative, so when the halogen gains the electron,
it becomes a single negative ion, while the alkali metal becomes
a single positive ion.
CITATION:
BBC - GCSE Bitesize: Alkali metals. (n.d.). Retrieved December 27, 2016, from http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/periodic_table/groupsrev1.shtml
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Webmaster@chemicalelements.com, Y. B. (n.d.). Chemical Elements.com - Alkali Metals. Retrieved December 27, 2016, from http://www.chemicalelements.com/groups/alkali.html