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The Curious Properties of Alkaline Earth Metals: Why Are They So Reactive?
The alkaline earth metals are six chemical elements in Group 2 of the periodic table, including barium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and ruthenium (Ra). There are striking similarities between these elements: they all appear bright silvery white at standard temperatures and pressures, and are relatively active metals. The common feature of these metals is that their outer s orbitals are satisfied - that is, the orbital has two complete electrons, and can easily lose these two electrons to form a cation with a +2 charge.
At the same time, these elements, like helium, have a complete outer electron structure, but helium is classified as a noble gas.
The chemical behavior of alkaline earth metals tends to behave according to their electronic configuration, which creates some trends among different elements. Although the chemical properties of strontium have not been fully studied, the chemical behavior of the first to fifth alkaline earth metals has been widely observed. Not only do these metals have lower melting and boiling points, but they are also very reactive with halogens and can form corresponding ionic compounds. In addition, except for beryllium, other metals may produce strong alkalinity when reacting with water to form hydroxyl groups, and should be handled with caution.
Heavy alkaline earth metals react more violently, so be aware of their potential hazards.
Chemical Properties
We learned that the chemical reaction of alkaline earth metals to halogens can form ionic halides, such as calcium chloride (CaCl2). At the same time, calcium, strontium and bismuth can also react with oxygen to produce corresponding oxides, such as strontium oxidation substance (SrO). The predictability of these interactions combined with their unique position in the periodic table results in the formation of two main types of compounds and corresponding chemical reactions.
As mentioned earlier, beryllium is an exception as its higher charge density means it will not react with water at room temperature. The compounds formed by beryllium are mostly covalent compounds, and although its fluoride is the most ionized beryllium compound, its melting point and conductivity are still low.
All alkaline earth metals have two electrons in their outermost shell. Therefore, losing these two electrons to form positively charged ions is their preferred state to obtain a stable electron shell.
Physical and Atomic Properties
Concerning the stability of these metals, isotopes of all six alkaline earth metals are present in varying concentrations in the Earth's crust and throughout the solar system, and their half-lives determine their nuclear stability. The first five metals have one, three, five, four and six stable isotopes respectively, for a total of nineteen stable nuclides. Relatively speaking, berkelium has no stable or primitive isotopes to speak of.
Historical background
Alkaline earth metals are named after their oxides, which behave alkaline when combined with water. These oxides are known as the basic components of alkaline earth metals. Historically, early chemists considered these non-metallic substances called "earth" to be water-insoluble and heat-resistant, and it was these properties that ultimately led to the recognition of these elements and their compounds.
Most alkaline earth metals were gradually isolated in a series of chemical electrolysis experiments from the late 18th to early 19th centuries. In particular, the discovery process of beryllium went through many experiments. It was not until 1898 that a relatively pure beryllium sample was obtained through electrolysis of a slightly stable compound.
Generally speaking, beryllium's electrical conductivity and its use in metallurgy make it important in military and other technologies, while magnesium has a wide range of applications in building and structural materials, not least because of its plasticity and strength , also because of its use in many alloys.
So, in the face of the properties and uses of these important metals, can we further explore how these chemical elements shape the future of our modern technology?
