Column 2A of the periodic table is home to the reactive alkaline earth metals. We find these elements in fireworks, vitamins, and even running through our own veins. Learn some properties and characteristics of this group of elements, and then take a quiz.
What are Alkaline Earth Metals?
The alkaline earth metals are all of the elements in the second column (column 2A) of the periodic table. This group includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). Alkaline earth metals have only two electrons in their outermost electron layer.
Alkaline earth metals get the name ‘alkaline’ because of the basic nature of the compounds they form when bonded with oxygen.
Properties and Characteristics
Alkaline earth metals in their pure forms are generally shiny and silvery. They rarely occur in their pure form, however, because they are very reactive. Alkaline earth metals have two electrons in their outermost electron layer, which take relatively little energy to remove. The energy it takes to remove an electron from an element is called the ionization energy. Alkaline earth metals have relatively low ionization energies for their first two electrons; because of this, alkaline earth metals exist with a 2+ charge most of the time. It is most common to find them in ionic compounds or as ions.
The more reactive metals in the series, calcium, barium and strontium, react vigorously with water at room temperature. Magnesium will react with water too, but only if it’s boiling.
As mentioned earlier, alkaline earth metals get the name ‘alkaline’ from the basic nature of the compounds they form when bonded with oxygen. When alkaline earth metal oxides are placed in water, the resulting product is basic.
Alkaline earth metals react with nonmetals to form ionic compounds. In these types of reactions, the alkaline earth metal gives up its outermost electrons to a nonmetal that is greedy for electrons. Reactions that involve electron exchange are called oxidation-reduction or redox reactions. The following is an example of magnesium reacting with oxygen to produce magnesium oxide.
Alkaline Earth Metals in Action
Like their very reactive neighbors in column 1A (the alkali metals), the alkaline earth metals don’t often occur in their pure, unionized form. Calcium and magnesium ions are an important component of human nutrition; calcium ions are necessary for healthy bones and teeth and magnesium ions are necessary for metabolism and muscle function.
Strontium, barium, and magnesium are key ingredients for a colorful and intense firework show. The bright reds come from strontium salts and the greens come from barium. Magnesium burns an intensely bright white.
Many naturally occurring compounds are made in part of alkaline earth metals. Peridot gems, recognizable as the birthstone for the month of August, contain magnesium. Beryllium makes up an important part of emeralds.
Radium is an extremely unstable and radioactive element. It is usually found in uranium ores and has no use for living organisms. While undergoing radioactive decay, radium releases energy that may be harmful to organisms.
Calcium occurs readily in the form of calcium carbonate (CaCO3). This compound is the main component of limestone and is a crucial ingredient in the shells of many marine creatures, from corals to sea snails. If you are a homeowner, you also may recognize calcium in the form of buildup on your faucets. Calcium and magnesium ions are present in untreated water known as hard water. These two ions react with soap and other detergents to make a hard, un-dissolvable substance that builds up in and around water pipes.
Let’s review. The alkaline earth metals are all of the elements in the second column of the periodic table. This group includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Alkaline earth metals get the name ‘alkaline’ because of the basic nature of the compounds they form when bonded with oxygen. Alkaline earth metals have relatively low ionization energies for their first two electrons; because of this, alkaline earth metals exist with a 2+ charge most of the time. It is most common to find them in ionic compounds, or as ions. Alkaline metals are found in many common objects such as fireworks, some gemstones, and hard water.
Properties of the Alkaline Earth Metals
- Often shiny and silvery
- Have relatively low ionization energies
- Often found in ionic compounds or as ions
- Rarely occur in pure form due to reactive nature
- Usually found with a 2+ charge
When you are finished, you should be able to:
- Identify the alkaline earth metals on the periodic table
- Name the elements of the 2A group
- State the properties of the alkaline earth metals
- Discuss the uses of the alkaline earth metals