Group VIA Nonmetals: Oxygen & Sulfur

VI A Group Nonmetals (Oxygen, Sulfur)

• Oxygen stands out as the most abundant element on Earth, constituting approximately 50% of its mass.
• With an electronegativity of 3.5, oxygen interacts with almost all metallic elements.
• Hydrogen compounds of Group VI A elements are more stable than those of Group V A due to their higher electronegativity; the opposite is true for oxygen compounds.
• Oxygen is found in 1400 minerals like quartz, mica, feldspar, clay, and limestone. It exists abundantly in chemical compounds and dissolved in water.
• The atmosphere contains 1015 tons of oxygen, while it makes up 65% of the human body.

Obtaining Oxygen

• Oxygen can be obtained by:

  • Supplying 1.air

  • Electrolysis of water: 2H2O → 2H2 + O2

  • Heating chromium trioxide: 2CrO3 → 2Cr + 3O2

  • Heating barium peroxide: BaO2 → Ba + O2

  • Heating potassium nitrate: 2KNO3 → 2KNO2 + O2

  • Heating potassium chlorate: 2KClO3 → 2KCl + 3O2

  • Heating potassium permanganate: 2KMnO4 → K2MnO4 + O2 + MnO2

• Oxygen has low solubility in water (3:100). Above 100 km, it exists in atomic form due to UV radiation (O2 → O + O).

Ozone (O3)

• Ozone is an allotropic form of oxygen with diamagnetic molecules.
• Oxygen is colorless, while ozone is a blue gas with higher polarity and polarizability.
• Ozone can be created from oxygen through electrical discharge: 3O2 → 2O3
• Ozone is also created in the atmosphere during lightning strikes 3O2 produces by lightning 2O3
• Reactions for ozone formation & reduction

  • C+2Н++2e- =-2,07 в

  • O+4H++4e-2HOE=+1,23 в.

• Ozone is a strong oxidizing agent, second only to fluorine in chemical activity
• Ozone does not react with inert gases, platinum nor gold
• Oxygen typically has a covalence of 4 and a maximum valence of II
• Oxygen reacts with the remaining nonmetals
• Oxides form covalent bonds when there is little difference in electronegativity between oxygen and nonmetals They are gases, volatile liquids, or easily soluble solids
• Nonmetal oxides dissolve in water to form acids.
• CO, NO, and N2O are neutral oxides, insoluble in water due to their strong molecular structures
• The acidity of a metal oxide increases with the oxidation state of the nonmetal

  • P4O10(K)+6H2O(water)=4H3PO4

  • SO3(K)+H2O(water)=H2SO4

  • Cl2O7(g)+H2O(water)=2HClO4

• Metal oxides are classified as basic, acidic, or amphoteric.

Metal Oxides

• Alkali and alkaline earth metal oxides dissolve in water, forming ionic bonds.
• Covalency in metal oxides increases with the oxidation state of the metal.
• Known oxygen compounds include peroxides, superoxides, and ozonides.
• The Ozonides K+ K+, are red in colour - 1e −→++1e→

Sulfur

• With a 3d-orbital, sulfur exhibits IV and VI valences.
• Sulfur atoms form strong bonds, making up 0.05% of the Earth's surface
• It can be found in free form and in minerals such as pyrite (FeS2), galena (PbS), anhydrite (CaSO4), and barite (BaSO4).
• Hydrogen sulfide (H2S) gas is also found in mineral water sources.
• Naturally, sulfur can be obtained from free deposits

Physical Characteristics

• At room temperature, sulfur exists in a rhombic form (α-sulfur), which does not dissolve in yellow water.

  • S-rhombic 940

  • monoclinic, B-sulfur (S8)

• Sulfur can be arranged in a corona structure like in the image

Hybridization

• Sulfur uses sp³ hybridization. Temperature affects its structure and magnetic properties:
  • S8 4500CS6 6500C↔S4 9000CS2↔15000C↔S
  • S2 is paramagnetic similar to O2 while the rest are diamagnetic.

Chemical properties of Sulfur

• Sulfur reacts with metals to form sulfides (S+MeMe2 Sn), and the metal’s valence determines the result
  • S+ O2→ SO2
  • S+ Г2 SCI2
• Sulfur can undergo disproportionation reactions: 3S+6NaOH =2+++3ЊО
• Sulfur can either gain or lose electrons in chemical reactions: S+2e- or S-4e54+

Compounds and Properties

• Sulfur reacts with oxygen to form sulfur dioxide (SO2)

  • S+ O2→ SO2 (4+)

• Sulfur can form various compounds with water, such as:

  • SU++↔++SQ-

  • SO2 + NaOH→ NaHSO3

• Hydro-sulfite can form: SO2 + 2NaOH→+Н2O

• Sulfur can act as both oxidizing and reducing agent.

Reactions of Sulfur

• Sulfur dioxide reacts with hydrogen sulfide to form sulfur and water: SO2+2H2S 3S+ 2Н2O ;

• Sodium sulfite reacts with oxygen to form sodium sulfate:2Na2SO3 + O2→ 2;

• Hydro-sulfites convert to pyro-sulfites at elevated temeratures where, 2 NaHSO3 – hydro-sulfites -Na2S2O5+H2O where Н 2S2O5 pyro-sulfuric acid is absent.

• Sulfur reacts with phosphorus pentachloride to form phosphorus oxychloride and thionyl chloride: SU+PCPOCl3 (oxychloride) +S+OCl₂

• Thionyl chloride is a reducing agent.

• Reactions involving thionyl chloride:

  • SOCI2+2H2O→2HCl+

  • +S→ - thiosulfate.

• Sodium thiosulfate reacts with hydrochloric acid to produce sodium chloride and unstable thio-sulfuric acid:

• Thio-sulfuric acid decomposes into sulfur dioxide, sulfur, and water: H2S2O3→ S+ SO2 +

• Thiosulfates are reducing agents.

• Sulfur reacts with chlorine in the presence of light or at 4°C to form sulfuryl chloride : huS+U+Cl2SC+4ºC

• Sulfuryl Chloride ыdissolves in hot water

Other Reactions involving Sulfur

• Reactions involving :

  • SOCI2+2H2O→2HCl+

  • SO2 + O22SO3, catalyst NO2

  • SO3 + - like oil, odorless and clear

• is a strong oxidizing agent.

Sulfates from Basic Metals

• Alkali and alkaline earth metal sulfates are thermally stable while sulfates of less active metals decompose.

• Decomposition examples:

  • ZnSO4 →ZnO +SO3

  • AgSO4→2Ag+SO2+O2

• Heating of hydrosulfates will yield 2NaHSO4→ to+ Н2О disulfate.

• If SO3 is dissolved in , oleum (oily) is formed, it exhibits strong oxidizing properties with an affinity for water.

Production of Sulfuric Acid

• Sulfuric acid is produced through the contact process (using V2 05 catalyst) n or the nitrosa process:

  • Al, Fe, Cr become passive in concentrated H2.

• Reactions with metals and concentrated H2SO4 depends on the metal activity and will result in:

  • +Me→ Н2 + metal sulphate.

• If the sulfuric acid is dilute will produce metal sulphate, as will more concentrated acids- the surface of Pb gets covered, preventing further reaction.

• Sulfates are salts of sulfuric acid and can contain crystalized water molecules. They have a range of uses eg salts: Na glauber KAI Aluminium potassium

Compounds containing sulfur

• Hydrogen sulfide (H2 S) gas solution in water - a weak acid: H₂ + S ® H2 S.
• Hydrogen sulfide is a toxic gas that affects hemoglobin. H2 S reacting with the Fe2+ in hemoglobin
• Sulfides and hydrosulfides dissolve well in water.

Properties Of Sulphides

• Coloured salts: red, yellow.
• Water soluble and can undergo hydrolyses
• Can dissolve in acids

Explore Group VIA nonmetals, focusing on oxygen and sulfur. Oxygen, Earth's most abundant element, interacts widely due to its high electronegativity and is crucial in minerals, water, and the atmosphere. Methods for obtaining oxygen including electrolysis of water and heating various compounds are examined.