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The heavier alkaline earth metals react more vigorously than the lighter ones. [2] The alkaline earth metals have the second-lowest first ionization energies in their respective periods of the periodic table [4] because of their somewhat low effective nuclear charges and the ability to attain a full outer shell configuration by losing just two ...
Radium is the heaviest known alkaline earth metal and is the only radioactive member of its group. Its physical and chemical properties most closely resemble its lighter congener, barium. [4] Pure radium is a volatile, lustrous silvery-white metal, even though its lighter congeners calcium, strontium, and barium have a slight yellow tint. [4]
Similar solutions are formed by the heavy divalent alkaline earth metals calcium, strontium, barium, as well as the divalent lanthanides, europium and ytterbium. The amide salt is quite insoluble and readily precipitates out of solution, leaving intensely coloured ammonia solutions of the alkali metals.
Radium (Ra, atomic number 88) is an almost pure-white alkaline earth metal, but it readily oxidizes, reacting with nitrogen (rather than oxygen) on exposure to air, becoming black in color. All isotopes of radium are radioactive ; the most stable is radium-226 , which has a half-life of 1601 years and decays into radon .
Sodium (Na) is an alkali metal. It is present in Earth's oceans in large quantities in the form of sodium chloride (table salt). Magnesium (Mg) is an alkaline earth metal. Magnesium ions are found in chlorophyll. Aluminium (Al) is a post-transition metal. It is the most abundant metal in the Earth's crust. Silicon (Si) is a metalloid.
As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium.
It is an alkaline earth metal, a relatively reactive group, although not nearly as reactive as the alkali metals. Like rubidium, it has 5 electron shells or energy levels, and in accordance with the Madelung rule it has two electrons in its 5s subshell. Strontium is a soft metal and is extremely reactive upon contact with water.
Francium is an alkali metal whose chemical properties mostly resemble those of caesium. [8] A heavy element with a single valence electron, [9] it has the highest equivalent weight of any element. [8] Liquid francium—if created—should have a surface tension of 0.05092 N/m at its melting point. [10]