Alkali metal

Atomic No.	Standard Atomic Weight	Name	Symbol	Picture
3	6.94	Lithium	Li
11	22.99	Sodium	Na
19	39.098	Potassium	K
37	85.468	Rubidium	Rb
55	132.91	Caesium	Cs
87	[223]	Francium	Fr	−

Alkali metals are the chemical elements in periodic table group 1, other than hydrogen. The term group 1 element can be used to include hydrogen.

They are silver-coloured when pure, soft and have only one valence electron. They like to make reactions in which they give up this single electron and then have a charge of +1. They react strongly with water and explode when wet, and because of this, they have to be stored in oil. Alkali metals are the first group (column) in the periodic table. They are never found in nature uncombined because they are unstable and they react fast to other elements. They bond well with all elements except the noble gases. When they are in air, they quickly turn black.

The alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (sometimes written cesium, although caesium is preferred) (Cs), and francium (Fr). Lithium is the least reactive. Although it was thought before that francium would be the most reactive, though it is very rare, it was more recently predicted that caesium is in fact more reactive than francium due to relativity.

The alkali metals

• Lithium is a very light metal. It is soft, silvery and you can cut it with a knife.

• Sodium is the most important alkali metal. One of the most important salts of sodium is sodium chloride (NaCl) (common 'table salt'). It also forms a hydroxide, sodium hydroxide (NaOH), which is commonly called 'caustic soda'. It is a very strong base.

• Potassium is commonly found in bananas.

• Rubidium is a metal that can make things like fireworks red.

• Caesium is a very heavy, poisonous metal and is the most reactive metal.

• Francium is a very dangerous, radioactive metal. Not much is known about it. However, based on the way the periodic table works, it might be like caesium.

All of the alkali metals explode in water due to their reactivity, but no one has ever seen francium in water. Once the francium is created, it only has 22 minutes before it decays into radium, and it's too radioactive to go near, so nobody has seen it in water.

Alkali Metal Media

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  Francium is here represented by Uraninite (uranium ore mostly composed of uranium dioxide (UO2), which contains 235U, which then decays into francium among other things. All samples were obtained commercially from online sellers (e.g. Luciteria, NovaElements, etc...)

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  Petalite, the lithium mineral from which lithium was first isolated

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  Johann Wolfgang Döbereiner was among the first to notice similarities between what are now known as the alkali metals.

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  Lepidolite, the rubidium mineral from which rubidium was first isolated

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  Dmitri Mendeleev's periodic system proposed in 1871 showing hydrogen and the alkali metals as part of his group I, along with copper, silver, and gold

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  Spodumene, an important lithium mineral

• Potassium reacts violently with water at room temperature

• Caesium reacts explosively with water even at low temperatures

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  Effective nuclear charge on an atomic electron