Metal

A metalan element that readily forms cationsbonds ionically. The metalsone ofthree groupselements as distinguished by their ionizationbonding properties, along withmetalloidsnonmetals. Onperiodic table,diagonal line drawn from boron (B)polonium (Po) separatesmetals fromnonmetals. Elements on this linemetalloids, sometimes called semi-metals; elements tolower leftmetals; elements toupper rightnonmetals.

Metals have certain characteristic physical properties: theyusually shiny, havehigh density,ductile malleable, usually have a high melting point,usually hard,conduct electricityheat well. These propertiesmainly because each atom exerts onlyloose hold on its outermost electrons (valence electrons); thus,valence electrons formsortsea aroundatoms. Most metalschemically stable, withnotable exception ofalkali metals alkaline earth metals, found inleftmost two groups ofperiodic table.

Nonmetalsmore abundantnature thanmetals, but metalsfact constitute most ofperiodic table. Some well-known metalsaluminium, copper, gold, iron, lead, silver, titanium, uranium,zinc.

An alloy ismixturemetallic properties that contains at least one metal element. Examplesalloyssteel (ironcarbon), brass (copperzinc), bronze (coppertin),duralumin (aluminiumcopper). Alloys specially designedhighly demanding applications, such as jet engines, may contain more than ten elements.

The oxidesmetalsbasic; thosenonmetalsacidic. The allotropesmetals tendbe lustrous, ductile, malleable,good conductorss, while nonmetals generally speakingbrittle (for solid nonmetals), lack luster, andinsulators.

In astronomy,metalany element other than hydrogen or helium. This distinctionsignificant because hydrogenhelium (togethertrace amountslithium) areonly elements that occur naturally withoutfusion activitystars. Thus,metallicity ofgalaxy or other objectan indicationpast stellar activity.