Alkaline Earth Metals
Definition and meaning of Alkaline Earth Metals in chemistry.
Alkaline earth metals are a group of metallic elements in Group 2 of the periodic table that form alkaline (basic) oxides and hydroxides. They are characterized by having two valence electrons in their outer shell and forming +2 cations in their compounds.
In more detail
These elements, which include magnesium, calcium, strontium, and barium, are more reactive than most transition metals but significantly less reactive than the alkali metals in Group 1. They never occur naturally as free elements due to their chemical reactivity, though their compounds are extremely abundant in nature, calcium carbonate comprises limestone and chalk, while magnesium sulfate is found in Epsom salt. The group shows increasing reactivity as you move down from beryllium to radium, reflecting the increasing ease of removing their valence electrons.
Key facts
| Group | Group 2 of the periodic table |
|---|---|
| Valence Electrons | 2 |
| Common Cation | +2 |
| Field | Inorganic Chemistry |
Calcium (Ca, atomic number 20) exemplifies the alkaline earth metals: it is essential for bone and tooth formation in animals and forms several important compounds, including calcium carbonate (CaCO3) in seashells and limestone, and calcium chloride (CaCl2) used as a de-icer.
Frequently asked questions
Why are alkaline earth metals called 'alkaline'?
They are called alkaline because their oxides and hydroxides react with water to form basic (alkaline) solutions, which have a pH greater than 7.
What is the difference between alkaline earth metals and alkali metals?
Alkaline earth metals (Group 2) have two valence electrons and form +2 cations, while alkali metals (Group 1) have one valence electron and form +1 cations. Alkali metals are significantly more reactive than alkaline earth metals.