What is Alkali Metals? | Types, Definition, Structure, Function & Facts
What is Alkali Metals?
Alkali Metals are a group of elements in the periodic table. They are all in the first column of the periodic table. The only element in the first column that is not usually considered an alkali metal is hydrogen. Hydrogen and the alkali metals make up the group 1 elements of the periodic table.
The alkali metals are all shiny, soft and highly reactive metals at standard temperature and pressure and easily lose their outermost electron to form +1 charged cations. They can all be cut easily with a knife due to their softness, revealing a shiny surface that quickly tarnishes in air due to oxidation by atmospheric moisture and oxygen (and in the case of lithium, nitrogen). Because of their high reactivity, they must be stored in oil to avoid any reaction with air and are found naturally only as salts and never as free elements.
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Cesium, the fifth alkali metal, is the most reactive of all metals. All alkali metals react with water, with heavier alkali metals more reactive than lighter metals.
What elements are Alkali Metals?
The elements of the alkali metals include lithium, sodium, potassium, rubidium, cesium, and francium. Click the links or see below for more details on each.
What are the similar properties of alkali metals?
Alkali metals share many similar properties, including:
They are shiny and soft metals.
They are very responsive.
They all have one valence electron in the outermost shell that they seek to lose in order to have a complete outer shell. That’s what makes them so responsive.
They are soft enough to cut with a knife.
When exposed to air, they tarnish due to oxidation.
They are not found in nature in the free elemental form, but are usually in the form of salts.
They react when in contact with water. Some of them will even explode on contact with water.
They are malleable, ductile and conduct electricity and heat well.
They have a low density compared to other metals.
Order of Abundance
The most abundant of the Alkali Metals on Earth is sodium. Here is the list in order:
- Sodium
- Potassium
- Lithium
- Rubidium
- Cesium
- Francium
Interesting Facts about Alkali Metals
Because they react strongly with air and water, they are often stored in oil.
Cesium and rubidium are used to make atomic clocks. Cesium watches are considered to be the most accurate of all watches.
Both sodium and potassium play important roles in biological life on Earth. We cannot live without them.
Sometimes cesium is also spelled “cesium”.
They prefer to form salts by combining with halogens.
The name “alkali” is derived from the Arabic word for “ash”.
Different alkali metals burn with different colored flames, including sodium (orange yellow), lithium (red), potassium (clove), rubidium (red) and cesium (blue or purple).
All alkali metals have odd atomic numbers.
They are considered more similar than any other group in the periodic table. Ammonium compounds have very similar properties to the heavier alkali metals.
Going down the periodic table, each alkali metal has an increasing atomic radius as well as increasing reactivity.