alkalineearth

Alkaline earth elements, commonly called alkaline earth metals, are the elements in Group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These metals are silvery-white, relatively lightweight, and highly reactive, especially with water and air. They all have two valence electrons and readily form divalent cations (M2+) in compounds. In their compounds they typically produce oxides with the formula MO and hydroxides M(OH)2, the latter of which are strongly basic when dissolved in water.

Chemistry and properties: Alkaline earths form oxides and hydroxides that are basic. Reactivity generally increases down the group, so calcium, strontium, and barium react noticeably with water to release hydrogen. They occur in nature only in mineralized forms and are not found free in the environment. Their chemistry is dominated by the divalent oxidation state, and their compounds are common in construction, industry, and technology.

Occurrence and production: The elements are abundant in the Earth's crust, especially calcium and magnesium. Common minerals include calcite and limestone (CaCO3), dolomite (CaMg(CO3)2), magnesite (MgCO3), gypsum (CaSO4), celestite (SrSO4), and witherite (BaCO3). Industrial production typically involves processing of these minerals or extraction from seawater and brines, followed by reduction or electrolysis to obtain the metals. The exact methods vary by element and application.

Uses and biology: Magnesium alloys are valued for light weight in aerospace and automotive uses; calcium compounds are essential in cement and lime production, and calcium plays a major role in biology and bone structure. Strontium and barium compounds have roles in electronics, magnets, fireworks, and medical imaging (barium sulfate for X-ray contrast). Beryllium is used in specialized aerospace and nuclear applications. Biologically, magnesium and calcium are essential nutrients for many organisms, while others in the group have limited or no essential roles. Safety considerations include toxicity concerns for certain soluble compounds and the radiological hazards associated with radium.