I II IIIIVVVI VIIVIIIIX X XI XIIXIII XIV XV XVI XVII XVIII XIX XX XXIXXII XXIII XXIV ● Homework
Learning ObjectivesTo recognize the trends in properties and also reactivity that the team 16 elements: the chalcogens.
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The chalcogens space the very first group in the p block to have actually no stable metallic elements. All isotopes of polonium (Po), the only metal in team 16, space radioactive, and only one element in the group, tellurium (Te), can also be explained as a semimetal. As in teams 14 and 15, the lightest aspect of team 16, oxygen, is uncovered in nature as the free element.
Of the group 16 elements, just sulfur was well-known in old times; the others to be not found until the so late 18th and 19th centuries. Sulfur is generally found as yellow crystalline shop of basically pure S8 in areas of intense volcanic task or approximately hot springs. As early as the 15th century BC, sulfur was used as a fumigant in Homeric greece because, once burned, it produces SO2 fumes that room toxic to many organisms, consisting of vermin hiding in the walls and under the floors the houses. Hence references come sulfur are typical in ancient literature, generally in the context of religious purification. In fact, the association of sulfur v the magnificent was for this reason pervasive the the prefixes thio- (meaning “sulfur”) and also theo- (meaning “god”) have the same root in old Greek. Though used mostly in the production of sulfuric acid, sulfur is likewise used to manufacture gunpowder and as a cross-linking agent because that rubber, which enables rubber to host its shape however retain the flexibility.
Group 16 is the very first group in the p block through no steady metallic elements.
Oxygen to be not found until 1771, as soon as the sweden pharmacist Carl Wilhelm Scheele discovered that heater compounds such as KNO3, Ag2CO3, and HgO created a colorless, odorless gas that supported combustion much better than air. The results were not published immediately, however, therefore Scheele’s work-related remained unknown until 1777. Unfortunately, this was almost two year after a paper by the English altoalsimce.orgist Joseph Priestley had actually been published, relenten the isolation of the very same gas by using a magnifying glass to emphasis the sun’s light ray on a sample the HgO. Oxygen is used mostly in the steel industry during the counter of crude oil iron to steel utilizing the Bessemer process. An additional important commercial use of oxygen is in the manufacturing of TiO2, i m sorry is typically used as a white colours in paints, paper, and also plastics.
Tellurium was discovered accidentally in 1782 by the Austrian altoalsimce.orgist Franz Joseph Müller von Reichenstein, the cook surveyor the mines in Transylvania who was also responsible because that the analysis of ore samples. The silvery-white metal had the same thickness as antimony but very different properties. Due to the fact that it was difficult to analyze, Müller dubbed it metallum problematicum (meaning “difficult metal”). The surname tellurium (from the Latin tellus, meaning “earth”) to be coined by another Austrian altoalsimce.orgist, young name Klaproth, who demonstrated in 1798 the Müller’s “difficult metal” was actually a brand-new element. Tellurium is used to color glass and also ceramics, in the manufacture of blasting caps, and also in thermoelectric devices.
Jöns Jakob Berzelius (1779–1848)
Berzelius to be born into a well-educated sweden family, however both parents died when he to be young. That studied medication at the university of Uppsala, whereby his experiments v electroshock therapy caused his understand to revolve to electroaltoalsimce.orgistry. Berzelius devised the system of altoalsimce.orgical notation the we use today. In addition, he found six aspects (cerium, thorium, selenium, silicon, titanium, and zirconium).
Because selenium and tellurium space altoalsimce.orgically similar to sulfur, they are usually discovered as boy contaminants in steel sulfide ores and also are typically recovered as by-products. Even so, they space as abundant in Earth’s crust as silver, palladium, and also gold. One of the finest sources of selenium and tellurium is the “slime” deposited during the electrolytic purification the copper. Both the these elements are notorious for the vile odors of countless of their compounds. For example, once the body absorbs even trace quantities of tellurium, dimethyltellurium <(CH3)2Te> is produced and also slowly released in the breath and perspiration, bring about an intense garlic-like smell that is typically called “tellurium breath.”
With your ns2np4 electron configurations, the chalcogens room two electrons brief of a fill valence shell. Hence in reactions through metals, they tend to acquire two extr electrons to type compounds in the −2 oxidation state. This propensity is biggest for oxygen, the chalcogen v the greatest electronegativity. The heavier, much less electronegative chalcogens deserve to lose either 4 np electrons or four np and two ns electron to type compounds in the +4 and +6 oxidation state, respectively, as shown in Table figure (PageIndex1). Just like the other groups, the lightest member in the group, in this instance oxygen, differs greatly from the others in size, ionization energy, electronegativity, and also electron affinity, so its altoalsimce.orgistry is unique. Additionally as in the various other groups, the second and third members (sulfur and also selenium) have similar properties due to the fact that of shielding effects. Only polonium is metallic, developing either the hydrated Po2+ or Po4+ ion in aqueous solution, depending on conditions.
|atomic fixed (amu)||16.00||32.07||78.96||127.60||209|
|atomic radius (pm)||48||88||103||123||135|
|density (g/cm3) at 25°C||1.31 (g/L)||2.07||4.81||6.24||9.20|
|electron affinity (kJ/mol)||−141||−200||−195||−190||−180|
|first ionization energy (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 point (°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 the reaction with H2||H2O||H2S||H2Se||none||none|
|product of reaction v N2||NO, NO2||none||none||none||none|
|product that reaction with O2||—||SO2||SeO2||TeO2||PoO2|
|product the reaction v X2||O2F2||SF6, S2Cl2, S2Br2||SeF6, SeX4||TeF6, TeX4||PoF4, PoCl2, PoBr2|
|standard palliation potential (E°, V) (E0 → H2E in acidic solution)||+1.23||+0.14||−0.40||−0.79||−1.00|
|type the oxide||—||acidic||acidic||amphoteric||basic|
|valence electron configuration*||2s22p4||3s23p4||4s24p4||5s25p4||6s26p4|
Reactions and also Compounds the Oxygen
As in teams 14 and also 15, the lightest team 16 member has actually the greatest propensity to kind multiple bonds. For this reason elemental oxygen is discovered in nature together a diatomic gas that consists of a net double bond: O=O. Similar to nitrogen, electrostatic repulsion between lone bag of electron on surrounding atoms prevents oxygen from developing stable catenated compounds. In fact, except for O2, all compounds the contain O–O bonds are possibly explosive. Ozone, peroxides, and superoxides room all perhaps dangerous in pure form. Ozone (O3), among the most an effective oxidants known, is provided to purify drinking water because it walk not develop the characteristics taste linked with chlorinated water. Hydrogen peroxide (H2O2) is therefore thermodynamically unstable that it has a tendency 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 team 16 has the greatest tendency to type multiple bonds.
Despite the toughness of the O=O link ((D_mathrmO_2) = 494 kJ/mol), (O_2) is exceptionally reactive, reacting straight with virtually all other aspects except the noble gases. Some properties that O2 and related species, such as the peroxide and superoxide ions, are in Table (PageIndex2). With couple of exceptions, the altoalsimce.orgistry that oxygen is restricted to an adverse oxidation states because of that high electronegativity (χ = 3.4). Unlike the other chalcogens, oxygen does not form compounds in the +4 or +6 oxidation state. Oxygen is 2nd only to fluorine in its capacity to stabilize high oxidation claims of steels in both ionic and covalent compounds. Because that example, ago is a secure solid that includes silver in the inexplicable Ag(II) state, vice versa, OsO4 is a volatile solid that has Os(VIII). Since oxygen is for this reason electronegative, the O–H bond is highly polar, producing a large bond dipole minute that provides hydrogen bonding much more important for compounds that oxygen 보다 for comparable compounds of the other chalcogens.
Metal oxides are usually basic, and also nonmetal oxides space acidic, conversely, oxides of aspects that lie on or close to the diagonal band of semimetals are typically amphoteric. A few oxides, such together CO and PbO2, space neutral and also do no react with water, aqueous acid, or aqueous base. Nonmetal oxides are commonly covalent compound in i m sorry the bonds between oxygen and the nonmetal room polarized (Eδ+–Oδ−). Consequently, a lone pair of electron on a water molecule can attack the partly positively fee E atom come eventually form an oxoacid. An instance is reacting sulfur trioxide v water to type sulfuric acid:
The oxides that the semimetals and also of elements such together Al the lie near the metal/nonmetal separating line are amphoteric, as we expect:
Oxides of metals tend to it is in basic, oxides of nonmetals often tend to be acidic, and also oxides of elements in or close to the diagonal band of semimetals are normally amphoteric.
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Predict the product(s) of every reaction and also write a well balanced altoalsimce.orgical equation for each reaction.SiO2(s) + H+(aq) → NO(g) + O2(g) → SO3(g) + H2O(l) → H2O2(aq) + I–(aq) →
AnswerSiO2(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)