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Properties of metals, metalloids and nonmetals

Periodic table color-coded to show metals, metalloids, and nonmetals.
The periodic table showing:
 metals  in most of the left and centre;
 metalloids  in a narrow diagonal band;
 nonmetals  in the right, and hydrogen

The chemical elements can be broadly divided into metals, metalloids and nonmetals according to their shared physical and chemical properties. All metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metals; and have at least one basic oxide. Metalloids are metallic-looking brittle solids that are either semiconductors or exist in semiconducting forms, and have amphoteric or weakly acidic oxides. Typical nonmetals have a dull, coloured or colourless appearance; are brittle when solid; are poor conductors of heat and electricity; and have acidic oxides. Most or some elements in each category share a range of other properties; a few elements have properties that are either anomalous given their category, or otherwise extraordinary.




Pure (99.97%+) iron chips, electrolytically refined, accompanied by a high purity (99.9999% = 6N) 1 cm3 cube

Metals appear lustrous (beneath any patina); form mixtures (alloys) when combined with other metals; tend to lose or share electrons when they react with other substances; and each forms at least one predominantly basic oxide.

Most metals are silvery looking, high density, relatively soft and easily deformed solids with good electrical and thermal conductivity, closely packed structures, low ionisation energies and electronegativities, and are found naturally in combined states.

Some metals appear coloured (Cu, Cs, Au), have low densities (e.g. Be, Al) or very high melting points, are liquids at or near room temperature, are brittle (e.g. Os, Bi), not easily machined (e.g. Ti, Re), or are noble (hard to oxidise) or have nonmetallic structures (Mn and Ga are structurally analogous to, respectively, white P and I).

Metals comprise the large majority of the elements, and can be subdivided into several different categories. From left to right in the periodic table, these categories include the highly reactive alkali metals; the less reactive alkaline earth metals, lanthanides and radioactive actinides; the archetypal transition metals, and the physically and chemically weak post-transition metals. Specialized subcategories such as the refractory metals and the noble metals also exist.


Tellurium, described by Dmitri Mendeleev as forming a transition between metals and nonmetals[1]

Metalloids are metallic looking brittle solids; tend to share electrons when they react with other substances; have weakly acidic or amphoteric oxides; and are usually found naturally in combined states.

Most are semiconductors, and moderate thermal conductors, and have structures that are more open than those of most metals.

Some metalloids (As, Sb) conduct electricity like metals.

The metalloids, as the smallest major category of elements, are not subdivided further.


25 ml of bromine, a dark red-brown liquid at room temperature

Nonmetals have open structures (unless solidified from gaseous or liquid forms); tend to gain or share electrons when they react with other substances; and do not form distinctly basic oxides.

Most are gases at room temperature; have relatively low densities; are poor electrical and thermal conductors; have relatively high ionisation energies and electronegativities; form acidic oxides; and are found naturally in uncombined states in large amounts.

Some nonmetals (C, black P, S and Se) are brittle solids at room temperature (although each of these also have malleable, pliable or ductile allotropes).

From left to right in the periodic table, the nonmetals can be subdivided into the polyatomic nonmetals which, being nearest to the metalloids, show some incipient metallic character; the diatomic nonmetals, which are essentially nonmetallic; and the monatomic noble gases, which are almost completely inert.

Comparison of propertiesEdit


Number of metalloid properties that resemble metals or nonmetals
(or that are reasonably distinct)
     Resemble metals        Relatively distinctive     Resemble nonmetals  
Properties compared: (36)   7 (19%) 25  (68%) 5 (13%) 
Physical (21)   5 (24%) 14  (67%) 2 (10%) 
 • Presentation & structure  (10)   2 (20%) 
 • Electron-related (6)   1
 • Thermodynamics (5)   2
Chemical (16)   2 (13%) 11  (69%) 3 (19%) 
 • Elemental chemistry (6)   3  (50%) 
 • Combined form chemistry (6)   2
 • Environmental chemistry (4) 

The characteristic properties of metals and nonmetals are quite distinct, as shown in the table below. Metalloids, straddling the metal-nonmetal border, are mostly distinct from either, but in a few properties resemble one or the other, as shown in the shading of the metalloid column below and summarized in the small table at the top of this section.

Authors differ in where they divide metals from nonmetals and in whether they recognize an intermediate metalloid category. Some authors count metalloids as nonmetals with weakly nonmetallic properties.[n 1] Others count some of the metalloids as post-transition metals.[n 2]


Physical and chemical properties[n 3]
Metals[8] Metalloids Nonmetals[8]
Presentation and structure
  • nearly all are shiny and grey-white
  • Cu, Cs, Au: shiny and golden[9]
  • shiny and grey-white[10]
  • most are colourless or dull red, yellow, green, or intermediate shades[11]
  • C, P, Se, I: shiny and grey-white
  • zero or low (mostly)[16] to intermediate[17]
  • often low
Deformability (as a solid)
  • brittle, when solid
  • some (C, P, S, Se) have non-brittle forms[n 6]
Poisson's ratio[n 7]
  • low to intermediate[n 9]
Crystalline structure at freezing point[47]
Packing & coordination number
  • close-packed crystal structures[48]
  • high coordination numbers
  • relatively open crystal structures[49]
  • medium coordination numbers[50]
  • open structures[51]
  • low coordination numbers
Atomic radius
  • intermediate to very large
  • 112–298 pm, average 187
  • small to intermediate: B, Si, Ge, As, Sb, Te
  • 87–123 pm, average 115.5 pm
  • very small to intermediate
  • 31–120 pm, average 76.4 pm
Allotropes[53][n 11]
  • around half form allotropes
  • one (Sn) has a metalloid-like allotrope (grey Sn, which forms below 13.2 °C[54])
  • all or nearly all form allotropes
  • some (e.g. red B, yellow As) are more nonmetallic in nature
Periodic table block
Outer s and p electrons
  • few in number (1–3)
  • except 0 (Pd); 4 (Sn, Pb, Fl); 5 (Bi); 6 (Po)
  • medium number (3–7)
  • high number (4–8)
  • except 1 (H); 2 (He)
Electron bands: (valence, conduction)
  • nearly all have substantial band overlap
  • Bi: has slight band overlap (semimetal)
Electron behaviour
  • "free" electrons (facilitating electrical and thermal conductivity)
  • valence electrons less freely delocalized; considerable covalent bonding present[57]
  • have Goldhammer-Herzfeld criterion[n 12] ratios straddling unity[61][62]
  • no, few, or directionally confined "free" electrons (generally hampering electrical and thermal conductivity)
Electrical conductivity
... as a liquid[70]
  • falls gradually as temperature rises[n 16]
  • increases as temperature rises
Thermal conductivity
Temperature coefficient of resistance[n 17]
  • nearly all positive (Pu is negative)[77]
  • nearly all negative (C, as graphite, is positive in the direction of its planes)[80][81]
Melting point
  • very high and solid at room temperature
  • mostly low and gas at room temperature
Melting behaviour
  • volume generally expands[82]
  • some contract, unlike (most)[83] metals[84]
  • volume generally expands[82]
Enthalpy of fusion
  • low to high
  • intermediate to very high
  • very low to low (except C: very high)
Elemental chemistry
Overall behaviour
  • metallic
  • nonmetallic
Ion formation
  • tend to form anions
  • seldom form covalent compounds
  • form many covalent compounds
Oxidation number
  • nearly always positive
  • positive or negative[89]
  • positive or negative
Ionization energy
  • relatively low
  • high
  • usually low
  • high
Combined form chemistry
With metals
With carbon
  • same as metals
With hydrogen (hydrides)
  • covalent, volatile hydrides[98]
  • covalent, gaseous or liquid hydrides
With oxygen (oxides)
  • solid, liquid or gaseous
  • few glass formers (P, S, Se)[103]
  • covalent, acidic
With sulfur (sulfates)
With halogens (halides, esp. chlorides) (see also[124])
  • typically ionic, involatile
  • generally insoluble in organic solvents
  • mostly water-soluble (not hydrolysed)
  • more covalent, volatile, and susceptible to hydrolysis[n 24] and organic solvents with higher halogens and weaker metals[125][126]
  • covalent, volatile[127]
  • usually dissolve in organic solvents[128]
  • partly or completely hydrolysed[129]
  • some reversibly hydrolysed[129]
  • covalent, volatile
  • usually dissolve in organic solvents
  • generally completely or extensively hydrolyzed
  • not always susceptible to hydrolysis if parent nonmetal at maximum covalency for period e.g. CF4, SF6 (then nil reaction)[130]
Environmental chemistry
Molar composition of Earth's ecosphere[n 25]
  • about 14%, mostly Al, Na, Ng, Ca, Fe, K
  • about 17%, mostly Si
  • about 69%, mostly O, H
Primary form on Earth
Required by mammals
  • large amounts needed: Na, Mg, K, Ca
  • trace amounts needed of some others
  • trace amounts needed: B, Si, As
  • large amounts needed: H, C, N, O, P, S, Cl
  • trace amounts needed: Se, Br, I, possibly F
  • only noble gases not needed
Composition of the human body, by weight
  • about 1.5% Ca
  • traces of most others through 92U
  • about 97% O, C, H, N, P
  • others detectable except noble gases

Anomalous propertiesEdit

There were exceptions…in the periodic table, anomalies too—some of them profound. Why, for example, was manganese such a bad conductor of electricity, when the elements on either side of it were reasonably good conductors? Why was strong magnetism confined to the iron metals? And yet these exceptions, I was somehow convinced, reflected special additional mechanisms at work…
Oliver Sacks
Uncle Tungsten (2001, p. 204)

Within each category, elements can be found with one or two properties very different from the expected norm, or that are otherwise notable.


Sodium, potassium, rubidium, caesium, barium, platinum, gold

  • The common notions that "alkali metal ions (group 1A) always have a +1 charge"[136] and that "transition elements do not form anions"[137] are textbook errors. The synthesis of a crystalline salt of the sodium anion Na was reported in 1974. Since then further compounds ("alkalides") containing anions of all other alkali metals except Li and Fr, as well as that of Ba, have been prepared. In 1943, Sommer reported the preparation of the yellow transparent compound CsAu. This was subsequently shown to consist of caesium cations (Cs+) and auride anions (Au) although it was some years before this conclusion was accepted. Several other aurides (KAu, RbAu) have since been synthesized, as well as the red transparent compound Cs2Pt which was found to contain Cs+ and Pt2− ions.[138]


  • Well-behaved metals have crystal structures featuring unit cells with up to four atoms. Manganese has a complex crystal structure with a 58-atom unit cell, effectively four different atomic radii, and four different coordination numbers (10, 11, 12 and 16). It has been described as resembling "a quaternary intermetallic compound with four Mn atom types bonding as if they were different elements."[139] The half-filled 3d shell of manganese appears to be the cause of the complexity. This confers a large magnetic moment on each atom. Below 727 °C, a unit cell of 58 spatially diverse atoms represents the energetically lowest way of achieving a zero net magnetic moment.[140] The crystal structure of manganese makes it a hard and brittle metal, with low electrical and thermal conductivity. At higher temperatures "greater lattice vibrations nullify magnetic effects"[139] and manganese adopts less complex structures.[141]

Iron, cobalt, nickel, gadolinium, terbium, dysprosium, holmium, erbium, thulium

  • The only elements strongly attracted to magnets are iron, cobalt, and nickel at room temperature, gadolinium just below, and terbium, dysprosium, holmium, erbium, and thulium at ultra cold temperatures (below −54 °C, −185 °C, −254 °C, −254 °C, and −241 °C respectively).[142]


  • The only element encountered with an oxidation state of +9 is iridium, in the [IrO4]+ cation. Other than this, the highest known oxidation state is +8, in Ru, Xe, Os, Ir, and Hs.[143]


  • The malleability of gold is extraordinary: a fist sized lump can be hammered and separated into one million paper back sized sheets, each 10 nm thick,[citation needed] 1600 times thinner than regular kitchen aluminium foil (0.016 mm thick).[citation needed]


  1. Bricks and bowling balls will float on the surface of mercury thanks to it having a density 13.5 times that of water. Equally, a solid mercury bowling ball would weigh around 50 pounds and, if it could be kept cold enough, would float on the surface of liquid gold.[citation needed]
  2. The only metal having an ionisation energy higher than some nonmetals (sulfur and selenium) is mercury.[citation needed]
  3. Mercury and its compounds have a reputation for toxicity but on a scale of 1 to 10, dimethylmercury ((CH3)2Hg) (abbr. DMM), a volatile colourless liquid, has been described as a 15. It is so dangerous that scientists have been encouraged to use less toxic mercury compounds wherever possible. In 1997, Karen Wetterhahn, a professor of chemistry specialising in toxic metal exposure, died of mercury poisoning ten months after a few drops of DMM landed on her "protective" latex gloves. Although Wetterhahn had been following the then published procedures for handling this compound, it passed through her gloves and skin within seconds. It is now known that DMM is exceptionally permeable to (ordinary) gloves, skin and tissues. And its toxicity is such that less than one-tenth of a ml applied to the skin will be seriously toxic.[144]


  • The expression, to "go down like a lead balloon" is anchored in the common view of lead as a dense, heavy metal—being nearly as dense as mercury. However, it is possible to construct a balloon made of lead foil, filled with a helium and air mixture, which will float and be buoyant enough to carry a small load.[citation needed]



  • The only element with a naturally occurring isotope capable of undergoing nuclear fission is uranium.[146] The capacity of uranium-235 to undergo fission was first suggested (and ignored) in 1934, and subsequently discovered in 1938.[n 28]


  • It is a commonly held belief that metals reduce their electrical conductivity when heated. Plutonium increases its electrical conductivity when heated in the temperature range of around –175 to +125 °C.[citation needed]



  • Boron is the only element with a partially disordered structure in its most thermodynamically stable crystalline form.[149]