4.6 GROUP PROPERTIES OF ELEMENTS (GROUP 6)

 GROUP VIA - OXYGEN FAMILY

• Non-metallic and exhibit oxidation state of -2, 0,+2,+4 and +6

• Hydrides are all gases, highly odoriferous and poisonous

 GROUP VIA - OXYGEN FAMILY

• Elements

• Oxygen 

• Suflur (S) 

• Selenium (Se) 

• Tellurium (Te) 

• Polonium (Po)

Oxygen (O^-2)

• aka

 “Empyreal air”, “Dephlogisticated air”, “Yne”

Oxygen (O^-2)

• physical properties

• Most abundant element / supports life 

• Oxides: Metallic, nonmetallic, amphoteric

• Chemically reactive (combines directly w/ elements except with the noble metals: Hg, Ag, Au, & Pt family)

Oxygen (O^-2)

• use

Used in the treatment of hypoxia / asphyxia

Oxygen (O^-2)

• container

Green

Oxygen (O^-2)

• 3 allotropes

• Nascent (O) 

• Atmospheric / molecular (O₂) 

• Ozone (O₃)

Ozone (O₃)

powerful OA (bleach, disinfectant)

Hyperbaric O₂

• 100% O₂, 2-3 atmosphere for treatment of hypoxia 

• Speed up healing of CO poisoning, gangrene, stubborn wounds, and infections in which tissues are starved for oxygen

Sulfur (S)

• aka

Sulfur (S)

• physical properties

Occurs in free state and in combination (sulfides, sulfates, sulfites)

Sulfur (S)

• source

• Crude furnace of calcarone 

  • Synthesized by Frasch process

Sulfur (S)

• allotropes

• alpha / rhombic S

• Beta/ monoclinic S

Alpha / Rhombic S-

at RT. Stable 

Beta / Monoclinic S-

• at equilibrium point (96^OC)

Sulfur (S)

• use

• Used in preparation of scabicidal & keratolytic ointment or lotion 

• Stimulant (stimulates hair growth)

• Cathartic 

• Depilatory agent /veet (as thioglycolate)

• Fumigant 

• Anti-dandruff

Amorphous s

Insoluble in CS₂

Liquid S

• Heating sal 160-180^OC 

• Insoluble in CS₂

Plastic S

Rubber-like

Precipitated S (milk of Sulfur, lac Sulfur)

• Boiling S with lime & precipitating filtered solution with HCI

• Very fine pale yellow powder, odorless, tasteless 

• CS₂ solubility: readily dissolves

Sulfurated ointment (10% sulfur)

• “AZUFRE” 

• Precipitated sulfur + mineral oil + white ointment

Sublimed S (flowers of sulfur)

• With impurities 

• Fine yellow powder with faint odor & taste 

• CS₂ solubility slowly & usually incompletely soluble

Sulfurated lime (Vleminckx’ solution)

Sublimed sulfur + lime (boiled)

Washed S

• Treating sublimed S with NH₃ (to dissolve impurities, particularly As & to remove traces of acid) 

• Characteristics similar to sublimed S

Sulfurated potash / Potassa sulfurate

• K₂S_x . K₂S₂O₅ (Liver of sulfur, Hepar sulfuris)

• Consists mainly of K polysulfide, K thiosulfate, & K sulfate

• Irregular, liver brown

• Possess H₂S odor

White lotion (USP)

• Sulfurated potash + ZnSO₄→ZnS (active ingredient 

• Topical anti-infective: Astringent, protective, mild antimicrobial & antifungal (tx of skin parasitic diseases, psoriasis, scabicide)

Selenium (Se)

• aka

“Selena”, “Moon”

Selenium (Se)

• physical properties

Essential trace element

Selenium (Se)

• pharmacologic use

• Promote absorption of Vitamin E 

• Used as anti-oxidant

Selenium (Se)

• industrial use

Rubber

Selenium Sulfide

AKA: Selsun Blue 

• Anti-dandruff

Tellurium (Te)

• Radioactive 

• Rare element in the oxygen group

Polonium (Po)

First radioactive element discovered by Curie

GROUP VIB - CHROMIUM SUBGROUP

• Exhibit oxidant state of +2 through +6

• +2 good reducing agent; +3 good oxidizing agent

• Valence: 6

GROUP VIB - CHROMIUM SUBGROUP

• elements

• Chromium 

• Molybdenum 

• Uranium

Chromium (Cr)

• physical properties

Essential trace element

Chromium (Cr)

• use

Glucose tolerance factor

Chromium (Cr)

• deficiency

Secondary hyperglycemia

Cr²⁺

Reducing agent / anti-oxidant

Cr³⁺

• Trace element (glucose tolerance factor) 

• Present in brown sugar

C⁶⁺

toxic

CrO₄^2-

Precipitant

K₂Cr₂O₇

strong oa

Molybdenum (Mo)

• physical properties

Essential trace element

Molybdenum (Mo)

• use

• Cofactor for flavin dependent enzymes, xanthine oxidase 

• Co-factor enzyme 

• For bacterial fixation of atmospheric N₂

Molybdenum Oxide (MoO₃)

+ FeSO₄: hematinic

Tungsten (W)

• aka

wolfram

Tungsten (W)

• use

filaments in light bulbs (increase Melt pt, decrease volatility)

Uranium

• Discovered by Becquerel (the Sl unit for radioactivity 1 Bq = 1 decay/sec) 

• Radioactive element used for manufacture of atomic bomb 

• Curie- non SI unit for radioactivity 

• No pharmaceutical use