GROUP -16

OXYGEN FAMILY

By :- Ajay Kr. MalikXII (Science)

Group 16 consist of 5 elements that are :- Oxygen(O) Sulphur(S) Selenium(Se) Tellurium(Te) Polonium(Po)

This family is known as oxygen family.

Element Atomic number

Electronic configuration

Oxygen 8 [He] 2s2 2p4

Sulphur 16 [Ne] 3s2 3p4

Selenium 34 [Ar] 3d10, 4s2 4p4

Tellurium 52 [Kr] 4d10, 5s2 5p4

Polonium 84 [Xe] 4f14, 5d10, 6s2 6p4

These elements(except polonium) are ore forming elements and thus called chalcogens.

Oxygen is gas while others are solid at room temperature.

Oxygen molecule is diatomic while molecule of other are more complex (exist as 8 atom ring).

PHYSICAL STATE

ss

ss

s

ss

s

Metallic character increases down the group.

Oxygen & Sulphur are non-metals. Selenium & Tellurium are metalloids. Polonium is metal.

Metallic And Non Metallic Character

Group 16 elements shows oxidation states of -2, +2, +4, +6.

Oxygen only shows -2 and +2 due to absence of d-orbitals.

-2 and +6 oxidation state decreases down the group.

+4 oxidation state increases down the group.

OXIDATION STATE

O S Se Te Po

Atomic Radii increase from Oxygen to Polonium

Ionisation Enthalpy decrease from Oxygen to Polonium

Electronegativity decrease from Oxygen to Polonium

CHEMICAL PROPERTIE

S

HYDRIDES :-

All the elements of group 16 form hydrides of type H2M type where M is O, S, Se, Te & Po.

Water is colourless, odourless liquid while other hydrides are colourless, poisonous gases with bad smell.

H HO S

H H

OXIDES :-

All the elements of group 16 form hydrides of type MO2, MO3 where M is O, S, Se, Te & Po.Elements Dioxides(MO2) Trioxide(MO3)

O -- O3

S SO2 SO3

Se SeO2 SeO3

Te TeO2 TeO3

Po PoO2 PoO3

Dioxides

SO2 and SeO2 are acidic oxides and are soluble in water. TeO2 and PoO2 are insoluble in water. These are amphoteric oxides as they dissolve in both acids and bases.

Trioxides

SO2 and SeO2 and TeO2 are acidic oxides and are soluble in water. Acidic nature decreases down the group.

HALIDES :-

Group 16 form a large no of halides of type EX6, EX4 and EX2 .

Stability of halides decreases in order

F->Cl->Br->I-

Hexahalides

Among all the hexahalides hexafluoride are only stable halides. They have octahedral structure.

TetraFluorides

SF 4 is gas, SeF 4 s liquid and TeF 4 is a solid. These fluorides have sp3d hybridisation. These have tetrahedral structures.

ANAMOLOUS

BEHAVIOUR

OF

OXYGEN

Oxygen is gas while others are solids. Oxygen is diatomic while rest are complex molecule. Oxygen is highly non-mettalic due to high value of electronegativity.