Editing Lead (section)

=== Bulk ===
Pure lead has a bright, shiny gray appearance with a hint of blue.{{sfn|Greenwood|Earnshaw|1998|p=372}} It tarnishes on contact with moist air and takes on a dull appearance, the hue of which depends on the prevailing conditions. Characteristic properties of lead include high [[density]], malleability, ductility, and high resistance to [[corrosion]] due to [[passivation (chemistry)|passivation]].{{sfn|Greenwood|Earnshaw|1998|pp=372–373}}

[[Image:Angeln zubehoer grundblei 01.jpg|thumb|left|Lead fishing weights]]
Lead's close-packed face-centered cubic structure and high atomic weight result in a density{{sfn|Thornton|Rautiu|Brush|2001|p=6}} of 11.34&nbsp;g/cm<sup>3</sup>, which is greater than that of common metals such as [[iron]] (7.87&nbsp;g/cm<sup>3</sup>), [[copper]] (8.93&nbsp;g/cm<sup>3</sup>), and [[zinc]] (7.14&nbsp;g/cm<sup>3</sup>).{{sfn|Lide|2005|pp=12–35, 12–40}} This density is the origin of the idiom ''to go over like a lead balloon''.{{sfn|Brenner|2003|p=396}}{{sfn|Jones|2014|p=42}}{{efn|[[British English]]: ''to go down like a lead balloon''.}} Some rarer metals are denser: [[tungsten]] and [[gold]] are both at 19.3&nbsp;g/cm<sup>3</sup>, and [[osmium]]—the densest metal known—has a density of 22.59&nbsp;g/cm<sup>3</sup>, almost twice that of lead.{{sfn|Lide|2005|pp=4–13, 4–21, 4–33}}

Lead is a very soft metal with a [[Mohs scale|Mohs hardness]] of 1.5; it can be scratched with a fingernail.{{sfn|Vogel|Achilles|2013|p=8}} It is quite malleable and somewhat ductile.{{sfn|Anderson|1869|pp=341–343}}{{efn|Malleability describes how easily it deforms under compression, whereas ductility means its ability to stretch.}} The [[bulk modulus]] of lead—a measure of its ease of compressibility—is 45.8&nbsp;[[Pascal (unit)|GPa]]. In comparison, that of [[aluminium]] is 75.2&nbsp;GPa; copper 137.8&nbsp;GPa; and [[Carbon steel|mild steel]] 160–169&nbsp;GPa.{{sfn|Gale|Totemeier|2003|pp=15–2–15–3}} Lead's [[Ultimate tensile strength|tensile strength]], at 12–17 MPa, is low (that of aluminium is 6 times higher, copper 10 times, and mild steel 15 times higher); it can be strengthened by adding small amounts of copper or [[antimony]].{{sfn|Thornton|Rautiu|Brush|2001|p=8}}

[[File:Lead-2.jpg|thumb|left|A sample of lead solidified from the molten state|alt=A disk of metal]]
The melting point of lead—at 327.5&nbsp;°C (621.5&nbsp;°F){{sfn|Lide|2005|p=12-219<!--do not correct punctuation here, please; it's a hyphen, that's how numeration of pages runs in the source. This is not a range of pages; this is one page.-->}}—is very low compared to most metals.{{sfn|Thornton|Rautiu|Brush|2001|p=6}}{{efn|A (wet) finger can be dipped into molten lead without risk of a burning injury.{{sfn|Willey|1999}}}} Its [[boiling point]] of 1749&nbsp;°C (3180&nbsp;°F){{sfn|Lide|2005|p=12-219}} is the lowest among the carbon-group elements. The [[Electrical resistivity and conductivity|electrical resistivity]] of lead at 20&nbsp;°C is 192 [[ohm|nanoohm]]-meters, almost an [[order of magnitude]] higher than those of other industrial metals (copper at {{val|15.43|u=nΩ·m}}; gold {{val|20.51|u=nΩ·m}}; and aluminium at {{val|24.15|u=nΩ·m}}).{{sfn|Lide|2005|p=12-45}} Lead is a [[Superconductivity|superconductor]] at temperatures lower than 7.19&nbsp;[[Kelvin|K]];{{sfn|Blakemore|1985|p=272}} this is the highest [[Superconductivity#phase transition|critical temperature]] of all [[type-I superconductor]]s and the third highest of the elemental superconductors.{{sfn|Webb|Marsiglio|Hirsch|2015}}