Alkaline Earth Metals

Alkaline earth metals are a group of chemical elements in Group 2 of the periodic table. They consist of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

These elements share the characteristic of having two electrons in their outer shell. For this reason, they readily lose both electrons and form ions with a charge of +2. When they form compounds, these are typically ionic bonds, meaning the electrons transfer completely to the other element.

Physical Properties

Generally, they are silvery-white, lustrous metals that conduct electricity and heat well. Compared to the alkaline metals (Group 1, such as sodium), they are harder and have higher melting points. As a rule, reactivity increases down the group: beryllium is quite unreactive, while barium and radium react readily with air and water.

Chemical Reactions

Elements of this group react with oxygen in air to form oxides. Calcium, strontium, and barium react with water, producing hydroxides and hydrogen gas. Magnesium requires hot water or steam to react readily, while beryllium does not react with water under normal conditions because a protective oxide layer forms on its surface.

Natural Occurrence and Uses

They do not occur naturally in pure form but only in minerals. Calcium is abundant in limestone (calcium carbonate) and gypsum; magnesium is found in seawater and various minerals. Calcium is an essential component of bones and teeth; magnesium is part of chlorophyll in plants. In industry, magnesium is used in lightweight alloys for aircraft, calcium in metal refining; barium compounds are sometimes used in medical imaging.