A general rewildtv.comistryrewildtv.comTextmaporganized about the textbookrewildtv.comistry: Principles, Patterns, and Applicationsby Bruce A. Averill


Learning Objectives

To know the patterns in properties and reactivity of the team 16 elements: the chalcogens.

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The chalcogens are the an initial group in the p block to have actually no stable metallic elements. All isotope of polonium (Po), the only metal in group 16, are radioactive, and also only one aspect in the group, tellurium (Te), can even be explained as a semimetal. As in groups 14 and 15, the lightest aspect of group 16, oxygen, is discovered in nature as the totally free element.

Of the team 16 elements, only sulfur was known in ancient times; the others to be not discovered until the so late 18th and also 19th centuries. Sulfur is typically found together yellow crystalline deposits of essentially pure S8 in areas of intense volcanic activity or about hot springs. As early as the 15th century BC, sulfur was supplied as a fumigant in Homeric greece because, as soon as burned, the produces SO2 fumes that room toxic to most organisms, including vermin hiding in the walls and under the floors of houses. For this reason references to sulfur are common in ancient literature, frequently in the context of spiritual purification. In fact, the combination of sulfur through the magnificent was for this reason pervasive that the prefixes thio- (meaning “sulfur”) and theo- (meaning “god”) have the same root in old Greek. Despite used primarily in the manufacturing of sulfuric acid, sulfur is additionally used come manufacture gunpowder and also as a cross-linking agent for rubber, which permits rubber to hold its shape yet retain that flexibility.

Group 16 is the first group in the p block through no steady metallic elements.

Oxygen to be not discovered until 1771, once the swedish pharmacist Carl Wilhelm Scheele found that heating compounds such as KNO3, Ag2CO3, and HgO produced a colorless, odorless gas that sustained combustion better than air. The outcomes were not published immediately, however, so Scheele’s work remained unknown till 1777. Unfortunately, this was almost two years after a record by the English rewildtv.comist Joseph Priestley had been published, relenten the isolation that the exact same gas by making use of a magnifying glass to emphasis the sun’s beam on a sample that HgO. Oxygen is used generally in the steel industry during the counter of crude oil iron come steel utilizing the Bessemer process. One more important commercial use of oxygen is in the production of TiO2, i m sorry is frequently used together a white pigment in paints, paper, and also plastics.

Figure (PageIndex1): A crystalline sulfur deposit. This sulfur deposit is located approximately a volcano vent in Kilauea Crater, Hawaii.

Tellurium was discovered accidentally in 1782 through the Austrian rewildtv.comist Franz Joseph Müller von Reichenstein, the chief surveyor the mines in Transylvania that was additionally responsible because that the analysis of ore samples. The silvery-white metal had the same thickness as antimony but really different properties. Because it was daunting to analyze, Müller dubbed it metallum problematicum (meaning “difficult metal”). The name tellurium (from the Latin tellus, definition “earth”) to be coined by an additional Austrian rewildtv.comist, young name Klaproth, that demonstrated in 1798 the Müller’s “difficult metal” was actually a brand-new element. Tellurium is offered to shade glass and also ceramics, in the produce of blasting caps, and also in thermoelectric devices.

Jöns Jakob Berzelius (1779–1848)

Berzelius to be born right into a well-educated swedish family, however both parents passed away when he to be young. He studied medicine at the university of Uppsala, where his experiments v electroshock therapy brought about his interests to turn to electrorewildtv.comistry. Berzelius devised the device of rewildtv.comical notation that we use today. In addition, he discovered six facets (cerium, thorium, selenium, silicon, titanium, and also zirconium).

api/deki/files/16918/pyrite.jpg?revision=1" />Pyrite (FeS2). Because of its lustrous golden yellow cubic crystals, FeS2 is sometimes mistaken for gold, giving rise come its common name “fool’s gold.” genuine gold, however, is much denser 보다 FeS2, and gold is soft and malleable rather than hard and also brittle.

Because selenium and tellurium room rewildtv.comically similar to sulfur, they space usually discovered as minor contaminants in metal sulfide ores and also are generally recovered as by-products. Also so, they are as plentiful in Earth’s crust as silver, palladium, and gold. Among the ideal sources the selenium and tellurium is the “slime” deposited during the electrolytic purification the copper. Both of these facets are infamous for the vile odors of countless of their compounds. Because that example, once the human body absorbs also trace quantities of tellurium, dimethyltellurium <(CH3)2Te> is produced and slowly exit in the breath and also perspiration, bring about an intense garlic-like smell the is generally called “tellurium breath.”

With their ns2np4 electron configurations, the chalcogens room two electrons quick of a filled valence shell. Hence in reactions v metals, they often tend to acquire two added electrons to type compounds in the −2 oxidation state. This tendency is greatest for oxygen, the chalcogen with the highest electronegativity. The heavier, much less electronegative chalcogens have the right to lose either 4 np electron or four np and also two ns electrons to kind compounds in the +4 and +6 oxidation state, respectively, as displayed in Table figure (PageIndex1). As with the other groups, the lightest member in the group, in this instance oxygen, differs considerably from the rather in size, ionization energy, electronegativity, and also electron affinity, therefore its rewildtv.comistry is unique. Likewise as in the various other groups, the 2nd and 3rd members (sulfur and also selenium) have comparable properties due to the fact that of shielding effects. Just polonium is metallic, forming either the sign language Po2+ or Po4+ ion in aqueous solution, depending on conditions.

Table (PageIndex1): Selected properties of the group 16 aspects PropertyOxygenSulfurSeleniumTelluriumPolonium *The configuration presented does not encompass filled d and f subshells. †The worths cited because that the hexacations room for six-coordinate ions and are only estimated values.
atomic fixed (amu) 16.00 32.07 78.96 127.60 209
atomic number 8 16 34 52 84
atomic radius (pm) 48 88 103 123 135
atomic symbol O S Se Te Po
density (g/cm3) in ~ 25°C 1.31 (g/L) 2.07 4.81 6.24 9.20
electron affinity (kJ/mol) −141 −200 −195 −190 −180
electronegativity 3.4 2.6 2.6 2.1 2.0
first ionization power (kJ/mol) 1314 1000 941 869 812
ionic radius (pm)† 140 (−2) 184 (−2), 29 (+6) 198 (−2), 42 (+6) 221 (−2), 56 (+6) 230 (−2), 97 (+4)
melting point/boiling allude (°C) −219/−183 115/445 221/685 450/988 254/962
normal oxidation state(s) −2 +6, +4, −2 +6, +4, −2 +6, +4, −2 +2 (+4)
product of reaction through H2 H2O H2S H2Se none none
product of reaction through N2 NO, NO2 none none none none
product that reaction through O2 SO2 SeO2 TeO2 PoO2
product of reaction v X2 O2F2 SF6, S2Cl2, S2Br2 SeF6, SeX4 TeF6, TeX4 PoF4, PoCl2, PoBr2
standard reduction potential (E°, V) (E0 → H2E in acidic solution) +1.23 +0.14 −0.40 −0.79 −1.00
type that oxide acidic acidic amphoteric basic
valence electron configuration* 2s22p4 3s23p4 4s24p4 5s25p4 6s26p4

Reactions and also Compounds of Oxygen

As in teams 14 and also 15, the lightest group 16 member has actually the greatest tendency to type multiple bonds. Therefore elemental oxygen is found in nature as a diatomic gas that consists of a net twin bond: O=O. Just like nitrogen, electrostatic repulsion between lone bag of electron on surrounding atoms prevents oxygen from forming stable catenated compounds. In fact, other than for O2, all compounds the contain O–O binding are perhaps explosive. Ozone, peroxides, and superoxides space all potentially dangerous in pure form. Ozone (O3), among the most an effective oxidants known, is supplied to purify drinking water due to the fact that it does not produce the characteristic taste connected with chlorinated water. Hydrogen peroxide (H2O2) is for this reason thermodynamically stormy that it has a propensity to experience explosive decomposition when impure:

<2H_2O_2(l) ightarrow 2H_2O_(l) + O_2(g) ;;; ΔG^o = −119; kJ/mol label1>

As in teams 14 and 15, the lightest aspect in group 16 has actually the greatest propensity to kind multiple bonds.

Despite the toughness of the O=O bond ((D_mathrmO_2) = 494 kJ/mol), (O_2) is exceptionally reactive, reacting directly with almost all other elements except the noble gases. Some properties of O2 and also related species, such as the peroxide and also superoxide ions, are in Table (PageIndex2). With couple of exceptions, the rewildtv.comistry of oxygen is minimal to an adverse oxidation states since of that high electronegativity (χ = 3.4). Unlike the various other chalcogens, oxygen does not kind compounds in the +4 or +6 oxidation state. Oxygen is second only to fluorine in its capability to stabilize high oxidation states of metals in both ionic and also covalent compounds. Because that example, back is a secure solid that consists of silver in the inexplicable Ag(II) state, vice versa, OsO4 is a volatile solid that has Os(VIII). Because oxygen is for this reason electronegative, the O–H bond is very polar, producing a large bond dipole minute that makes hydrogen bonding much an ext important for compounds the oxygen 보다 for similar compounds the the various other chalcogens.

Table (PageIndex2): some Properties the O2 and also Related Diatomic types SpeciesBond OrderNumber of Unpaired e−O–O street (pm)* *Source of data: Lauri Vaska, “Dioxygen-Metal Complexes: towards a unified View,” accounts of rewildtv.comical research 9 (1976): 175.
O2+ 2.5 1 112
O2 2 2 121
O2− 1.5 1 133
O22− 1 0 149

Metal oxides space usually basic, and nonmetal oxides are acidic, conversely, oxides of aspects that lied on or near the diagonal tape of semimetals are usually amphoteric. A few oxides, such together CO and also PbO2, space neutral and also do not react v water, aqueous acid, or aqueous base. Nonmetal oxides are typically covalent compound in which the bonds in between oxygen and also the nonmetal space polarized (Eδ+–Oδ−). Consequently, a lone pair of electron on a water molecule can strike the partially positively charged E atom come eventually type an oxoacid. An example is reacting sulfur trioxide v water to form sulfuric acid:

The oxides the the semimetals and of facets such as Al that lie near the metal/nonmetal separating line room amphoteric, as we expect:

Oxides of metals tend to be basic, oxides the nonmetals tend to it is in acidic, and oxides of elements in or close to the diagonal band of semimetals are normally amphoteric.

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Exercise (PageIndex2)

Predict the product(s) of each reaction and write a well balanced rewildtv.comical equation because that each reaction.

SiO2(s) + H+(aq) → NO(g) + O2(g) → SO3(g) + H2O(l) → H2O2(aq) + I–(aq) →


SiO2(s) + H+(aq) → no reaction 2NO(g) + O2(g) → 2NO2(g) SO3(g) + H2O(l) → H2SO4(aq) H2O2(aq) + 2I−(aq) → I2(aq) + 2OH−(aq)