A metal (frae Greek μέταλλον métallon, "mine, quarry, metal") is a material (an element, compoond, or alloy) that is teepically haurd whan in solit state, opaque, shiny, an haes guid electrical an thermal conductivity. Metals are generally malleable—that is, thay can be haimered or pressed permanently oot o shape withoot brakkin or crackin—as weel as fusible (able tae be fused or meltit) an ductile (able tae be drawn oot intae a thin wire). Aroond 90 o the 118 elements in the periodic cairt are metals; the ithers are nonmetals or metalloids, tho elements near the boondaries o ilk category hae been assigned variably tae aither (hence the lack o an exact coont). Some elements appear in baith metallic an non-metallic forms.
Astropheesicists uise the term "metal" tae refer collectively tae aw elements in a starn that are hivier nor the lichtest twa, hydrogen an helium, an nae juist tradeetional metals. A starn fuses lichter atoms, maistly hydrogen an helium, tae mak hivier atoms ower its lifetime. Uised in that sense, the metallicity o an astronomical object is the proportion o its matter made up o the hivier chemical elements.
Mony elements an compoonds that are nae normally clessifee'd as metals acome metallic unner heich pressurs; thir are formed as metallic allotropes o non-metals, for ensaumple, pheesicists war able tae keep Hydrogen in its solit state unner mair nor 3 million times the atmospheric pressur an deduce its metallic properties.
The strenth an resilience o metals has led tae thair frequent uise in heich-rise biggin an brig construction, as weel as maist vehicles, mony hame appliances, tuils, pipes, non-illuminatit signs an railwey tracks. Precious metals war historically uised in cunyies.
- metal. Encyclopædia Britannica
- John C. Martin. "What we learn from a star's metal content". New Analysis RR Lyrae Kinematics in the Solar Neighborhood. Archived frae the original on 29 Juin 2016. Retrieved 7 September 2005.
- Crew, BEC. "Physicists Achieve Early Stages of a New, Solid State of Hydrogen". sciencealert.com. sciencealert.com. Retrieved 7 Januar 2017.
|Wikimedia Commons haes media relatit tae Metals.|