Question: What causes an element to have an increased metallic character?
About the article "Periodic table", section "Metallic character".

Candidate passages:
Salted versions of both fission and fusion weapons can be made by surrounding the core of the explosive device with a material containing an element that can be converted to a highly radioactive isotope by neutron bombardment.
When the bomb explodes, the element absorbs neutrons released by the nuclear reaction, converting it to its radioactive form.
The explosion scatters the resulting radioactive material over a wide area, leaving it uninhabitable far longer than an area affected by typical nuclear weapons.
In a salted hydrogen bomb, the radiation case around the fusion fuel, which normally is made of some fissionable element, is replaced with a metallic salting element.
Salted fission bombs can be made by replacing the neutron reflector between the fissionable core and the explosive layer with a metallic element.
The energy yield from a salted weapon is usually lower than from an ordinary weapon of similar size as a consequence of these changes.
The radioactive isotope used for the fallout material would be a high intensity gamma ray emitter, with a half-life long enough that it remains lethal for an extended period.
It would also have to have a chemistry that causes it to return to earth as fallout, rather than stay in the atmosphere after being vaporized in the explosion.
One example of a possible salted bomb would be a cobalt bomb, which would produce the radioactive isotope cobalt-60 (60Co).
Other radioactive isotopes that have been suggested for salted bombs include gold-198 (198Au), tantalum-182 (182Ta) and zinc-65 (65Zn).
Sodium-24 has also been proposed as a salting agent.
The UK tested a 1 kiloton bomb incorporating a small amount of cobalt as an experimental radiochemical tracer at their Tadje testing site in Maralinga range, Australia, on September 14, 1957. 
Nomenclature and history.
Derivation and other names.
The word metalloid comes from the Latin "metallum" ("metal") and the Greek "oeides" ("resembling in form or appearance").
Several names are sometimes used synonymously although some of these have other meanings that are not necessarily interchangeable: "amphoteric element," "boundary element," "half-metal," "half-way element," "near metal," "meta-metal," "semiconductor," "semimetal" and "submetal".
'Amphoteric element' is sometimes used more broadly to include transition metals capable of forming oxyanions, such as chromium and manganese.
'Half-metal' is used in physics to refer to a compound (such as chromium dioxide) or alloy that can act as a conductor and an insulator.
'Meta-metal' is sometimes used instead to refer to certain metals (Be, Zn, Cd, Hg, In, Tl, β-Sn, Pb) located just to the left of the metalloids on standard periodic tables.
These metals are mostly diamagnetic and tend to have distorted crystalline structures, electrical conductivity values at the lower end of those of metals, and amphoteric (weakly basic) oxides.
'Semimetal' sometimes refers, loosely or explicitly, to metals with incomplete metallic character in crystalline structure, electrical conductivity or electronic structure.
Examples include gallium, ytterbium, bismuth and neptunium.
The names "amphoteric element" and "semiconductor" are problematic as some elements referred to as metalloids do not show marked amphoteric behaviour (bismuth, for example) or semiconductivity (polonium) in their most stable forms. 
Under standard conditions germanium is a brittle, silvery-white, semi-metallic element.
This form constitutes an allotrope technically known as "α-germanium", which has a metallic luster and a diamond cubic crystal structure, the same as diamond.
At pressures above 120 kbar, a different allotrope known as "β-germanium" forms, which has the same structure as β-tin.
Along with silicon, gallium, bismuth, antimony, and water, it is one of the few substances that expands as it solidifies (i.e.
freezes) from its molten state.
Germanium is a semiconductor.
Zone refining techniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 1010, making it one of the purest materials ever obtained.
The first metallic material discovered (in 2005) to become a superconductor in the presence of an extremely strong electromagnetic field was an alloy of germanium with uranium and rhodium.
Pure germanium is known to spontaneously extrude very long screw dislocations.
They are one of the primary reasons for the failure of older diodes and transistors made from germanium; depending on what they eventually touch, they may lead to an electrical short. 
Iron is an essential element for human beings.
The control of this necessary but potentially toxic substance is an important part of many aspects of human health and disease.
Hematologists have been especially interested in the system of iron metabolism because iron is essential to red blood cells.
In fact, most of the human body's iron is contained in red blood cells' hemoglobin, and iron deficiency is the most common cause of anemia.
When body levels of iron are too low, then hepcidin in the duodenal epithelium is decreased.
This causes an increase in ferroportin activity, stimulating iron uptake in the digestive system.
An iron surplus will stimulate the reverse of this process.
In individual cells, an iron deficiency causes responsive element binding protein (IRE-BP) to bind to iron responsive elements (IRE) on mRNAs for transferrin receptors, resulting in increased production of transferrin receptors.
These receptors increase binding of transferrin to cells, and therefore stimulating iron uptake. 
Metallic Squad characters are a second line of planet heroes toys that took most of the original heroes and gave them a metallic uniform and new accessories.
"Designed by Uranus “Yuri” to deflect solar radiation even in the highest recorded temperatures in the galaxy, these cool new uniforms really come in handy when Black Hole “Professor Darkness” gets too hot to handle!
"The character Star Hollywood is unique to the Metallic Squad line.
Metallic squad characters for Sun Commander, Mars Digger, and Jupiter Gustus have not been released.
Metallic Mercury Zip Metallic Mercury Zip has a hover vehicle.
Metallic Venus Dazzle Metallic Venus Dazzle has a larger lava gun.
Metallic Earth Ace Metallic Earth has comes with a Jet Pack.
Metallic Moon Lunar Metallic Moon Lunar comes with a moon buggy.
Metallic Saturn Rings Metallic Saturn Rings comes with a Ring Gun.
Metallic Uranus Yuri Metallic Uranus Yuri comes with a suction gun and a small gun.
Metallic Neptune Tune Neptune Tune comes with a small sea serpent.
Metallic Pluto Shiver Pluto Shiver comes with a Plutonian Polar Bear with a cannon.
Metallic Star Shooter Metallic Star Shooter comes with a surf board and disc gun.
Metallic Star Hollywood Metallic Star Hollywood comes with a motorcycle.