Group 2 And 17

Front 1

Trend down the group 2 and 17

Back 1

Increasing nuclear charge due to increase in number of protons, increasing shielding effect due to increase of inner shell electrons, effective nuclear charge remains approximately constant.

In addition , valence electrons are further away from the nucleus due to increase in number of principal quantum shell . Valence electrons experiences weaker nuclear attraction .

Front 2

Effect of weaker nuclear attraction on atomic radius , IE, electronegativity and m.p/b.p

For group 2

Back 2

Weaker nuclear attraction

-> atomic/ ionic radius increase

-> Less energy required to remove valence electron, first IE decreases

-> ability to attract shared pair of electron in covalent bond decreases, electronegativity decreases

-> ionic radii increase and the charge density of cation decrease down the group -> weaker metallic bond

Front 3

Effect of weaker nuclear attraction on atomic radius, IE, Electronegativity, bp/volatility, and BE of group 17

Back 3

Weaker nuclear attraction

-> atomic/ ionic radius increase

-> Less energy required to remove valence electron, first IE decreases

-> ability to attract shared pair of electron in covalent bond decreases, electronegativity decreases

Halogens have sms-> idid, down the group , no of e increase, e cloud size larger and more polarisable, stronger idid-> mp/bp increases, volatility decreases.

Bond energy decreases (except for fluorine which is so small that repulsion occurs between the lone pair of electron which weakens the F-F bond) Atomic size increase, extent of effective overlap decreases, bond energy decreases

Front 4

Oxidising properties of group 17 down the group

Back 4

Eocell becomes less positive -> less readily reduced-> oxidising power decreases

Front 5

Oxidising strength of group 17 - which is strongest to weakest

And who displaces who

Back 5

Cl2> Br2> I2

Stronger oxidising halogen (more reactive) displaces the weaker oxidising halogen(less reactive)

Cl2 + 2Br- -> Br2 + 2Cl- ( orange solution of Br2 evolved )

Cl2 + 2I- -> I2 + Cl- ( brown solution of I2 aq formed with black solid of insoluble I2 / when organic solvent is added, I2 dissolved to give a purple organic layer)

Same for Br2 and I-

Front 6

Reactions of halogens and thiosulfate. Cl2/ Br2 and I2

Back 6

Cl2 / Br2 are stronger oxidising agents than I2

Seen in their reactions with thiosulfates. ( different products are formed)

Cl2 and Br2-> S2O32- oxidised to SO42- (+2 to +6)

I2-> S2O32- oxidised to S4O62- (+2 to +2.5)

Front 7

Trend of Thermal stability of group 17 halides down the group.

Back 7

As the size of halogens increase, there is smaller extent of effective overlap between the s orbital of H atom and p orbital of halogen atom . This results in weaker H-X covalent bond down the group .

BE and thermal stability decreases.

Front 8

Chemical properties - based on IE and E knot (oxidising power/ reactivity )

Of group 2

Back 8

E knot less positive - >ease of losing electrons increases- reactivity increases

-> reducing power increases -> stronger reducing agent

Ionisatiom energy -> ease of atoms losing valence electron to form cation increases, reactivity and reducing power increases. Thus stronger reducing agent.