Calcium vs. Magnesium

Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air.

Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.

A silvery, moderately hard alkaline-earth metal that constitutes approximately 3.6 percent of the earth's crust and is a basic component of most animals and plants. It occurs naturally in limestone, gypsum, and fluorite, and its compounds are used to make plaster, quicklime, Portland cement, and metallurgic and electronic materials. Atomic number 20; atomic weight 40.08; melting point 842°C; boiling point 1,484°C; specific gravity 1.54; valence 2. See Periodic Table.

A light, silvery-white, moderately hard metallic element that in ribbon or powder form burns with a brilliant white flame. Obtained chiefly from magnesite, dolomite, and bodies of salt water, it is used in structural alloys, pyrotechnics, flash photography, and incendiary bombs. Atomic number 12; atomic weight 24.305; melting point 650°C; boiling point 1,090°C; specific gravity 1.738 (at 20°C); valence 2. See Periodic Table.

The chemical element (Symbol Ca), with an atomic number 20. It is a soft, silvery-white alkaline earth metal which occurs naturally as carbonate in limestone and as silicate in many rocks.

The chemical element (symbol Mg) with an atomic number of 12. It is a light, easily flammable, silvery-white alkaline earth metal.

(countable) An atom of this element.

A light silver-white metallic element of atomic number 12, malleable and ductile, quite permanent in dry air but tarnishing in moist air. It burns, forming (the oxide) magnesia, with the production of a blinding light (the so-called magnesium light) which is used in signaling, in pyrotechny, or in photography where a strong actinic illuminant is required. Its compounds occur abundantly, as in dolomite, talc, meerschaum, etc. Symbol Mg. Atomic weight, 24.305. Specific gravity, 1.75.

An elementary substance; a metal which combined with oxygen forms lime. It is of a pale yellow color, tenacious, and malleable. It is a member of the alkaline earth group of elements. Atomic weight 40. Symbol Ca.

a light silver-white ductile bivalent metallic element; in pure form it burns with brilliant white flame; occurs naturally only in combination (as in magnesite and dolomite and carnallite and spinel and olivine)

a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals