I B group elements, Cu,Ag,AuPhysical Properties

Property/Element Cu Ag AuAtomic radius(A) 1.28 1.44 1.50Density (g/cm3) 8.98 10.54 19.43

Hardness(Mohs) 2.5-3 2.5-2.7 2.5m.p.(0C) 1083 960.5 1063b.p.(0C) 2310 1950 2600

Standard electrod potential,E0(250,V)

M+/MM2+/M+

M3+/M2+

+0.522+0.345 +0.799

+1.39+1.70

-+1.50

Electrical conductivity (Hg=1)

55.6 63.9 38.5

Thermal conductivity (Ag=1)

0.94 1.0 0.75

Clark (%) 7 x 10-2 2 x 10-5 5x10-7

O.S. I, II, III I, II, III I, II, IIIC.N. 4,6 4,6 4,6

IIB group elements, Zn,Cd,Hg

Property/Element Zn Cd HgAtomic radius(A) 1.38 1.54 1.57Density (g/cm3) 7.14 8.64 13.56

Hardness(Mohs) 2.5 2m.p.(0C) 419.4 320.9 -38.89b.p.(0C) 907 767 356.9

Standard electrod potential,E0(250,V)

M2+/M+0.52

+0.80 +1.70

Electrical conductivity (Hg=1)

16.3 14.9 1

Thermal conductivity (Ag=1)

0.26 0.23 0.02

Clark (%) 1.2 x 10-2 3x10-5 4x10-5

O.S. II II II

Chemical Properties

chemical reactivity decreases down the groupReactant Cu Ag AuWet air 2Cu + O2 + CO2+H2OCuCO3.Cu(OH)2 - -O2(air) CuO (t=2000C) black

Cu2O(t=8000C)brown, orange- -

S, H2S Cu2S, CuS (t=250C) Ag2S(1800C)

Au2S3-black

X2 CuX2 AgX AuBr3

Conc.acids

3Cu+8HNO33Cu(NO3)2+2NO+4H2OCu +2H2SO4CuSO4 + SO2 + 2H2O

Cu + 4HCl + O22CuCl2 + 2H2O

reactionwith

HNO3,H2SO4

-

Acetic acid

2Cu + 2CH3COOH + O2Cu(CH3COO)2.Cu(OH)2

- -

NH3 2Cu + 8NH3 + O2 + H2O2[Cu(NH3)4](OH)2

Aqua regia

H[AuCl4]

C No direct reactions2[M(NH3)2]NO3+C2H2M2C2+2NH4NO3+2NH3

M=Cu(I), Ag(I)Au + HNO3 + 4HCl H[AuCl4] + NO + 2H2O2H[AuCl4] + 3H2S Au2S3 + 2HClStability of O.S.Cu(I) (d10) – diamagnetic, colourless ; unstable state:disproportion : 2Cu+ Cu2+ + CuAg(I)- stable state –diamagnetic, colouless Soluble salts : AgNO3, AgClO4,AgF Insoluble salts : Ag2SO4, AgClAu(I) impure compounds : -mixtures of Au(I), Au(III), Au(0)disproportion : 6Au+ + 3H2O Au2O3 + 4Au + 6H+

Cu(II) (d9)–paramagnetic,absorption,600-900 nm-blue-greenAg(II) unstable state, oxidant : AgF2,AgOAu(II) – unknown

Cu(III) –(d8) –few compoundsAg(III) –few compounds : AgO(s) contains Ag(I) + Ag(III)Au(III)- characteristic state

Chemical properties- IIB group elements

Zn is more reactive, Hg is different after H2

Reactant Zn Cd HgWet air ZnO +ZnCO3.3Zn(OH)2 -O2 ZnO

whiteCdOwhite

Hg2O,HgOyellow

H2O(vap) M + H2O MO + H2 -S,Se.Te MS,Mse,MTeAcids Nonoxidant:

M + 2HCl MCl2 + H2

Oxidant M + 2H2SO4MSO4 + SO2 + 2H2O3M + 8HNO33M(NO3)2 + 2NO +4H2O4M + 10HNO34M(NO3)2+NH4NO3+3H2O

Only with oxidantacids

Alkalies Zn + KOH + 2H2O K[Zn(OH)3] + H2

no no

NH3

solutionZn + 4NH3 + 2H2O [Zn(NH3)4](OH)2+H2

no no

N2 No direct reactions3Zn + 2NH3Zn3N2 + 3H2

3M(NH2)2 Zn3N2 +9H2 + 2N2 (M=Zn,Cd,Hg)C No direct reactions

M + C2H2 ZnC2 + H2 (M=Zn,Cd)ZnO + 3C ZnC2 + COHg2(NO3)2 + CaC2 Hg2C2 + Ca(NO3)2

Why all Hg(I) compounds are diamagnetic (as solids, in solutions) ?

The majority of Hg(I) salts are colourless, insolubleDo you know two coloured salts?

Important uses of Cu,Ag and Au:Copper Silver, Gold

pure electrolyte Ag–no use in practice owing to its

-electrical wires and cablesalloys-simple brasses (Cu + 45%Zn)tube for condensers,radiatorsclocks, watches-special brasses (Cu+Fe+Al+Sn+Si)ship-building-brass with high Cu content(tombac)similar Audecorative articlescheap jewelry-copper-nickel alloy- constantanthermocouples-bronzes (Cu + Sn)-machine-building

softnessAlloys are used as-Ag-Cujewelry,coins,laboratory utensils-Ag-Znaccumulators with good electrical characteristicsand low mass and volume(K)- Ag2O (A) Zn (spongy)-Au- alloys Au-Ag electrical contacts, dentary technics, jewelry24 carats-pure Au18 carats- 75%Au,12.5%Ag+ 12.5%Cuwhite Au 80%Au + 15-20%Nired Au – 40-60% Au + 30-50% Cu + others : Ag,Ni,Zn

Silver salts–production of photografic materials-films,paper,glass Colloidal solutions of Ag (protargolum, collargolum)-stabilized with special additions – disinfection of mucous membranesUses of Zn, Cd, Hg:Zn- coatings (not effective in highly humid air,sea water)alloys brasses (Zn-Cu alloys)manufacture of galvanic dry cells (Zn – MnO2 in a paste of NH4Cl)Cd -as rods in nuclear reactors for controlling the rate of the chain reaction (cd absorbss slow neutrons)-alkaline accumulators-alloys–Cu alloys with 1%Cd--for making telegraph, telephone,trolleybus wires (a greater strength and wear resistence than Cu)Hg – cathode (production of NaOH, Cl2) catalyst –organic synthesis-amalgams (Fe does not form an amalgam, Hg can be transpoted in steel vessels

Biochemistry of the elements Cu, Zn,Cd,Hg

a variety of copper enzimes occur in plants and animals

3 types having : - distinctive geometries - different ligand environments - different O.S for copperType Geometry of

centerO.S. Ligands

Type I (blue Cu enzimes):AzurinPlastocyaninLaccase Electron-carrier proteins

Distorted Td Trigonal bipyramidTrigonal

Cu(II) or

Cu(I)Absorption assigned to Cys(S)Cu2+

(LMCT)

N and S

Type IITyrosinaseAscorbate oxidaseOxygenation reactions

TrigonalSquare planar5-coordinatedOh distorted

Cu(I)Cu(II)

Type IIIhemocyaninOxygen transport

Square planar5-coordinatedOh distorted

Binuclear Cu(II)Strong antiferomagneticcoupling

1970 – Zn is crucial to DNA and RNA synthesis and to cell devisionMetal center in Zinc-finger proteins- is a complex compound with Td coordination with two his and two cys

Mercury vapour is very toxic and may cause serious poisoningDo not keep vessels with Hg openDemercurizers : - sulphur powder

- 20% solution of FeCl3

- 10% solution of KMnO4 acidified with HCl

Cu, Ag, Au COMPOUNDS

OxidesM2O (M=Cu,Ag)CuO + Cu → Cu2O (brown)CuSO4 + 2NaOH → Cu(OH)2 + Na2SO4

2Cu(OH)2 + C6H12O6 → Cu2O + C6H12O7 + 2 H2O

2AgNO3 + 2NaOH → Ag2O + 2NaNO3 + H2OAg2CO3 → Ag2O + CO2

covalent compounds with a great thermal stability, Ag2O (3000C) → 2Ag + 1/2O2

insoluble in water, soluble in NH3 and in conc. acids:[Cu(NH3)2]OH, [CuX2]-

Cu2O + H2SO4 → CuSO4 + Cu + H2OAg2O + 2KCN + H2O → 2K[Ag(CN)2] + 2KOH

MO (M=Cu,Ag) black powdersCu(OH)2 → CuO + H2OCu(NO3)2 → CuO + 2NO2 + 1/2O2

CuCO3 .Cu(OH)2 → 2CuO + CO2 + H2O

Ag + O3 → AgO + O2 (decomposes t>1000C)

Au2O3 .nH2OHAuCl4 + 3NaOH → Au (OH) 3 + 3NaCl + H2O + HClAu(OH)3 (140-1500C) → Au2O3 . n H2O by drying in air is obtained a yellow-brownish powder, Au2O3.nH2O ~HAuO2

amphoteric properties : Au(OH)3 + 4HCl → H[AuCl4] + 3H2OAu(OH)3 + 4NaOH → Na[AuO2] + 3H2O Give some examples of halides and oxosalts with knowing uses or with interesting structuresAuCl3 , english green, Cu(CH3COO)2 . H2O