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The elements become progressively more metallic down the column.

The elements in this group have six electrons in their outer electronic shell. Thus, each element in this group has a tendency to gain two electron, to form a doubly charged negative ion, which has the stable electronic configuration of its nearest neighboring Nobel Gas element in the periodic table. As we proceed down the oxygen group we find a trend from nonmetal to metal. Oxygen, Sulfur, Selenium are all nonmetals, Tellurium is a metalloid and Polonium is a metal. Oxygen and sulfur are the 2 most important members of this group and they share many similarities in their patterns of reactivity.

Generally speaking down a p block group the element becomes more metallic in chemical character. However, in going down group 6, electrons are less tightly held; hence metallic behavior is observed. The table below shows how group 6 elements differ.

down group 6/16 ===>

property\Zsymbol, name

'8'O Oxygen

'16'S Sulphur

'34'Se Selenium

'52'Te Tellurium

'84'Po Polonium (radioactive)

Period

2

3

4

5

6

Appearance (RTP)

colourless gas

yellow solid (monoclinic/rhombic allotropes)

silver metalloid or red powder allotropes

silver white metalloid

radioactive silvery solid

melting pt./oC

-218

117

217

450

254

boiling pt./oC

-183

445

685

990

962

density/gcm-3

<0.1

2.1

4.8

6.2

9.3

1st IE/ kJmol-1

1314

1000

941

869

812

atomic covalent or metallic radius/pm

73 (cov)

102 (cov)

117 (cov), 190 (met)

135 (cov), 210 (met)

167 (met)

X2- ion radius/pm

140

184

198

221

230

electronegativity

3.44

2.58

2.55

2.10

2.00

simple electron config.

2,6

2,8,6

2,8,8,6

2,8,18,18,6

2,8,18,32,18,6

electron configuration

[He]2s22p4

[Ne]3s23p4

[Ar]3d104s24p4

[Kr]4d105s25p4

[Xe]4f145d106s26p4

principal oxidation states

-2, +1, (+2)

-2, +2, +4, +6

-2, +2, +4, +6

-2, +2, +4, +6

-2, +2, +4, +6

property\Zsymbol, name

'8'O Oxygen

'16'S Sulphur

'34'Se Selenium

'52'Te Tellurium

'84'Po Polonium



Chemical properties of polonium.

1) it has six valence electrons and exhibits variable valences of 2,4 and 6
2)it is a radioactive metal
3) it shows allotropy
4)it forms an amphoteric oxide, PoO2
5)it forms tetra and hexa Halides

6) The table below contains more chemical properties of polonium


Electronegativity according to Pauling

2.0

Vander Waals radius

0.164 nm

Isotopes             

12

Energy of first ionization

813.0 kJ.mol -1

Valence Electron Potential (-eV)

-12.5

Heat of Fusion

60.1kJ/mol

Electrochemical Equivalent

3.8986g/amp-hr



Physical properties of polonium

1.       It’s flammable

2.       Physical state is solid at 20°C

3.       The table below is the continuation of some physical properties of Polonium

Melting point

254°C

Boiling point

962°C

Density

9.51 g.cm-3 at 20°C

Enthalpy of Vaporization

60.3 kJ/mole

Atomic radius

1.53 Ǻ = 153 pm

Crystal structure

Monoclinic

Covalent Radius

1.46 Ǻ = 146 pm

Atomic Volume

22.23cm³/mol

Atomic Mass Average

208.9824

Coefficient of lineal thermal expansion/K-1

23E-6

Electrical and thermal Conductivity

0.0219 106/cm Ωand 0.2 W/cmK respectively

Enthalpy of Atomization

134 kJ/mole @ 25°C

Electrical resistivity

40 10-8 Ω m

The tellurium is borders the line and run diagonally across the Periodic Table, has properties that are characteristic of both metals and nonmetals, hence it’s called Metalloid.

Sources:


Chemistry explained-physical and chemical properties
http://www.chemistryexplained.com/elements/L-P/Polonium.html#ixzz1tkmkgeDJ

Lenntech- chemical properties
Read more:
http://www.lenntech.com/periodic/elements/po.htm#ixzz1tki8HNha

http://environmentalchemistry.com/yogi/periodic/Po.html

http://campus.dyc.edu/cpcfiles/DDay6cpc022.pdf

http://textbook.s-anand.net/ncert/class-11/chemistry/3-classification-of-elements-and-periodicity-in-properties

Metal - Survey Of The Periodic Table - Elements, Properties, Metallic, and Electrons - JRank Articles http://science.jrank.org/pages/4255/Metal-Survey-periodic-table.html#ixzz1tl2gn6Qo

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