These include direct industrial building use of clays, silica sand and stone. Most silicon is used commercially without being separated, and indeed often with little processing of compounds from nature. Over 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen. It is most widely distributed in dusts, sands, planetoids and planets as various forms of silicon dioxide (silica) or silicates. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure free element in nature.

However, its final name, suggested in 1831, reflects the more chemically similar elements carbon and boron. Controversy about silicon's character dates from its discovery: silicon was first prepared and characterized in pure form in 1824, and given the name silicium (from Latin: silicis, flints), with an -ium word-ending to suggest a metal. It is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table. Silicon (symbol Si) is a group 14 metalloid.

The most useful compounds of aluminium, at least on a weight basis, are the oxides and sulfates. Structural components made from aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The chief ore of aluminium is bauxite.Īluminium is remarkable for the metal's low density and for its ability to resist corrosion due to the phenomenon of passivation. Instead, it is found combined in over 270 different minerals. Aluminium metal is too reactive chemically to occur natively. It makes up about 8% by weight of the Earth's solid surface. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It is not soluble in water under normal circumstances. Magnesium ions are sour to the taste, and in low concentrations help to impart a natural tartness to fresh mineral waters.Īluminium (symbol Al) or aluminum ( American English) is a silvery white member of the boron group of chemical elements and a p-block metal classified by some chemists as a post-transition metal. Since magnesium is less dense than aluminium, these alloys are prized for their relative lightness and strength. Commercially, the chief use for the metal is as an alloying agent to make aluminium-magnesium alloys, sometimes called ' magnalium' or 'magnelium'. The metal is now mainly obtained by electrolysis of magnesium salts obtained from brine. The free metal burns with a characteristic brilliant white light, making it a useful ingredient in flares. The free element (metal) is not found naturally on Earth, as it is highly reactive (though once produced, it is coated in a thin layer of oxide, which partly masks this reactivity). Due to the magnesium ion's high solubility in water, it is the third most abundant element dissolved in seawater. It is relatively abundant because it is easily built up in supernova stars by sequential additions of three helium nuclei to carbon (which in turn is made from three helium nuclei). Magnesium is the fourth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle. It is the eighth most abundant element in the Earth's crust and the ninth in the known universe as a whole. Magnesium (symbol Mg) is an alkaline earth metal and has common oxidation number +2. The octet rule generally applies to period 3 in the same way as to period 2 elements, because the 3d subshell is normally non-acting. This makes all eight elements analogs of the period 2 elements in the same exact sequence. There is a 3d subshell, but-in compliance with the Aufbau principle-it is not filled until period 4. In a quantum mechanical description of atomic structure, this period corresponds to the buildup of electrons in the third ( n = 3) shell, more specifically filling its 3s and 3p subshells. All of the period 3 elements occur in nature and have at least one stable isotope. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements.

Period number of magnesium