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The Secret of Bauxite: Do you know what is special about the compounds of alkaline earth metals?
Alkaline earth metals are six chemical elements in the second group of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These elements all exhibit similar properties at standard temperature and pressure: they are all shiny, silvery white, and relatively reactive. It is noteworthy that the outer s-block orbit of alkaline earth metals is fully loaded: that is, the orbit contains two electrons, which the alkaline earth metals easily lose to form a cation with a positive charge of +2.
Except helium, all known alkaline earth metals can be found in nature, although the presence of radium is only manifested through the decay chains of uranium and thorium, and not as a pristine element.
Chemical Properties and Reactions
Alkaline earth metals show regular patterns in their chemical behavior. With the exception of radium, the other five metals react with halogens to form alkaline earth halides, and with oxygen to form oxides, such as strontium oxide (SrO). Calcium, strontium, and barium can also react with water to form hydrogen and their respective hydroxides (magnesium reacts more slowly). In particular, alkaline earth metals must be handled with care in practice, as their reactivity can lead to dangerous chemical reactions.
Physical and atomic properties
Alkaline earth metal isotopes exist in varying concentrations in the Earth's crust and throughout the solar system. Beryllium, magnesium, calcium, strontium, and barium each have varying amounts of stable isotopes, of which beryllium-9, magnesium-24, -25, and -26, and calcium-40 are the more common stable isotopes. Radium, on the other hand, has no stable isotopes. For older isotopes, such as calcium-48 and barium-130, their half-lives are 5.6×1019 and 1.6×1021 years, respectively, far exceeding the current age of the universe.
In the long run, identifying and understanding the properties of alkaline earth metal isotopes will not only enrich our understanding of elements, but may also open up new paths for future scientific research.
History and Discovery
Alkaline earth metals are named after their oxides, "alkaline earths". Early chemists called them non-metallic substances that are insoluble in water and heat-resistant. Antoine Lavoisier made a particularly outstanding contribution in the process of discovering that these "earths" were not elements but compounds.
The history of many elements can be traced back to ancient times. For example, lime was used in building materials as early as 7000-1000 BC; and magnesium compounds were first discovered in 1618. Early chemical practices laid the foundation for later scientific development.
Although beryllium was discovered in 1797, people only knew about certain beryllium compounds before 1910, until large-scale beryllium was obtained through electrolysis and other technical means.
Application of alkaline earth metals
Alkaline earth metals have different important uses in modern industry. Beryllium has potential applications in the military field, such as as a p-type dopant in the electronics industry; while magnesium has outstanding advantages in structural materials, especially in the aerospace and automotive industries, to reduce weight. In addition, calcium is also an extremely important reducing agent in the smelting process.
As technology continues to develop, the application of alkaline earth metals is also expanding. From water treatment to chemical production to advanced materials engineering, their influence is gradually penetrating into people's lives.
Have you ever thought about how alkaline earth metals will be integrated into our lives in the future?
