These metals are all very reactive and can easily lose their electrons. The alkali metals are all silver-colored, soft, and have relatively low melting points.
Discovery of Alkali Metals
Alkali metals are named after the Arabic word “alkali” which means ashes or burnt salt. This is because they react with water to form highly basic solutions capable of corroding most things. The name is also a reminder that these compounds were originally developed in the industry from the ashes of plants where it forms as visible salt.
In the context of chemistry, an alkali metal is any chemical element that belongs to group 1 in the periodic table. When they are ionized in a solution they produce a solution that has a pH close to 14.
Group 1 elements have 1 electron in their outer shell which they can easily lose giving them a +1 charge. Because the alkali metals have only one electron in their valence shell, they are extremely reactive and form ionic bonds with several different elements.
There are no set physical or chemical properties that allow chemists to identify an alkali metal.
Some of the More Common Properties They Use Include:
Relative atomic mass: This is how we identify metals in general. It is just the average mass per atom and it will not be accurate for all elements
A relative number of valence electrons: This can be calculated by knowing the number of protons and neutrons in an atom. For example, potassium has 19 protons and 21 neutrons which gives it 39 total electrons. Since the atomic number is 19, potassium has 1 valence electron per atom.
Softness: This can be tested by rubbing an object on metal to see if it can mark the surface of the metal. Alkali metals have low values for metal hardness which makes them easy to mark.
Alkali metals are all silvery in color due to the metallic properties of these elements. They are incredibly soft and can be cut with a knife because they lack the inert core of non-metals like carbon. This is because their outer electron shell has only one valence electron instead of the usual two. This makes them extremely reactive because it is easy for them to lose their valence electron. Since they are so reactive, alkali metals tend to be stored in mineral oil since this slows down the reaction with water.
Chemical Properties:
Alkali metals react vigorously when combined with oxygen and water, which is why they are stored in mineral oil. They also react with acids to form salts and release hydrogen gas. Due to the strong chemical reactions, alkali metals tend to be stored in containers that shield them from any contact with oxygen or moisture.
