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(Video) Group 1 - The Alkali Metals | The Periodic Table | Properties of Matter | Chemistry | FuseSchool

by FuseSchool - Global Education

This video will teach you about the properties of alkali metals, which are group $1$ on the periodic table. Here's a quick summary:

• The alkali metals (Lithium, Sodium, Potassium, Rubidium, Caesium, and Francium) have similar properties and are soft metals.
• They are highly reactive with water.
• They float on top of water.
• When they react with water, they produce hydrogen gas and their corresponding metal hydroxide. This makes an alkaline solution.

Alkali Metals of the Periodic Table

The alkali metals are in group 1A of the periodic table, or the column furthest to the left. The alkali metals consist of elements: lithium (Li), sodium (Na), potassium (K). Rubidium (Rb), cesium (Cs), and Francium (Fr).

Some properties of alkali metals are:

• Appearance - soft and shiny in their pure form.

• Reactivity - They are highly reactive metals. They have the tiny ionization energies and electron affinities. So, they easily lose electrons to form cations.

• Found in - typically found combined with other elements to create compounds. Usually have a +1 charge.

• Except for hydrogen, they are solid at room temperature.

Reactivity of Alkali Metals

Since these chemical elements are highly reactive, they are often used in chemistry reactions.

Alkali metals react vigorously with water, so they are very well known as they are extremely violent. Solid alkali metal is added to water and a basic solution is formed. Usually this reaction is accompanied by vigorous bubbling, heat, and even flames.

Let's look at the balanced chemical equation for the reaction between sodium and water: $$2\ Na(s)\ +\ 2\ H_2O(l)\ \rightarrow\ 2\ Na^+(aq)\ +\ 2\ OH^-(aq)\ +\ H_2(g)$$

When combined with halogens they form ionic salts called halides.

Example of a halide formation (specifically the formation of sodium chloride): $$2\ Na (s)\ +\ Cl_2(g) \rightarrow\ 2\ NaCl(s)$$

Alkali metals are very reactive with oxygen and the solid compounds are often stored in organic liquids, like oils. The oil coats the surface and prevents oxygen in the air from reaching the surface. When they react with $O_2$, oxides are formed.

Example of a peroxide formation: $$2\ Na(s)\ + O_2(g) \rightarrow\ Na_2O_2(s)$$