d & f block Flashcards by Hector .

Why is ns^0-2 written in d orbital valence shell electronic config?

Since Pd has 0 e`s in S orbital

How well did you know this?

Not at all

Perfectly

What are transition elements?

Those which have incompletely filled d-orbitals in ground and excited (oxidation) state

How well did you know this?

Not at all

Perfectly

Why are Zn, Cd & Hg not transition metals?

They have completely filled d-orbitals even after losing e’s from s orbital

How well did you know this?

Not at all

Perfectly

Zn & Hf occur together in nature. Why?

Due to same properties like atomic size

How well did you know this?

Not at all

Perfectly

All groups have metal behavious except for

group 12

How well did you know this?

Not at all

Perfectly

When no of unpaired e’s are more, bonding in metal

increases

How well did you know this?

Not at all

Perfectly

Down the group, atomisation enthalpy

increases

How well did you know this?

Not at all

Perfectly

what is enthalpy of atomization?

Energy needed to break the bond to atoms

How well did you know this?

Not at all

Perfectly

Why does atomic size decrease and gradually increase again across the period?

Due to shielding effect, nucleus is not able ot hold all e’s

How well did you know this?

Not at all

Perfectly

What is lanthanoid contraction?

gradual decrease in the atomic and ionic size of lanthanoids with an increase in atomic number

How well did you know this?

Not at all

Perfectly

Why is lanthanoid contraction seen in 5d & 6s series & 4d and 5d series?

14 e’s offer poor shielding effect from the element Hf which causes decrease in atomic size

How well did you know this?

Not at all

Perfectly

Why does density of 3d elements increase from Sc to Zn?

Atomic mass increases

How well did you know this?

Not at all

Perfectly

Why is ionisation enthalpy for 3d series irregular?

Due to irregularity in atomic size, it is lower for Cr due to absence of change in config while Zn has change in 4s config. b

How well did you know this?

Not at all

Perfectly

If reduction potential is high, its stabitlity is

less in aq solution

How well did you know this?

Not at all

Perfectly

Why is Cu1+ less stable than Cu2+?

Cu1+ has greater reduction potential and Cu2+ is surrounded by many water molecules due to which hydration enthalpy increases so it is stable

How well did you know this?

Not at all

Perfectly

What happens when Cu+ is present in aq. sol?

It undergoes oxidation & reduction at the same time called disproportionation rn.

How well did you know this?

Not at all

Perfectly

Why does Cu have +ve potential?

2nd ionisation enthalpy is very high due to which sum of enthalpies is +ve

How well did you know this?

Not at all

Perfectly

Why does Mn show a less tendency to get reduced?

After losing 2 e’s, it has stable half filled d orbital and -ve potential

How well did you know this?

Not at all

Perfectly

If potential is +ve, it will show more tendency to

get reduced

How well did you know this?

Not at all

Perfectly

Ni has -ve potential due to

high hydration enthalpy

How well did you know this?

Not at all

Perfectly

why is there irregularity in potentials?

Due to irregularity in sublimation & ionisation enthalpies

How well did you know this?

Not at all

Perfectly

The stability of divalent ions decrease. Why?

Since the potentials are becoming less -ve across the period.

How well did you know this?

Not at all

Perfectly

Why is Mn2+ resistant to oxidation but Fe2+ is not?

Due to half filled orbitals in Mn2+

How well did you know this?

Not at all

Perfectly

Why is reduction potential of Mn3+ high?

It is easy for Mn3+ to gain 1 e’ to be stable

How well did you know this?

Not at all

Perfectly

Co3+ & Mn3+ are ________ agents

oxidising

Ti2+, Cr2+ & V2+ are __________ agents

reducing

Which elements doesn't react with dilute acids at room temp?

Ti & V

Why Cu will not react with acid to liberate H2?

It has +ve potential

Which only shows +1 state?

Which shows max oxidation states?

Why transition elements show variable oxidation states?

(n-1)d and ns e's are involved in bond formation, pairing of e's takes place

Why does Mn show many oxidation states?

Due to 5 unpaired e's in 'd' & 2 in 's'

Commonly seen oxidation state in group 15 elements

+3 & +5

Why does +3 stability increase down the group?

Due to inert pair effect where nucleus holds e's in s orbitals which causes increase in nuclear charge & reluctance in bond formation of e's

Which oxidation state is stable for p block?

lower

Which oxidation state is stable for d block?

higher

For Mo & W, which is stable?

Why does K2Cr2O7 act as good oxidising agent?

Since it is stable when it gets reduced to +3 state

Why are MoO3 & WO3 not good oxidising agents?

They are already stable in +6 state so they don't show a tendency to get reduced

Lowest state seen in 3d series

0 in the compound [Ni(CO)4]

Highest states are seen in

Oxide & flourides

Highest states are seen in oxide & flouride. Why?

Due to small sized electro -ve elements, so they are able to oxidise metal to higher state

Why is highest state of an element seen in oxide?

Due to ability of oxygen to form multiple bonds with the metal

Which magnetic moment is seen in transition elements?

spin

What decides spin MM & color?

unpaired e's

Why are compds formed by Sc3+,Ag+ & Zn2+ colourless?

Since they don't have unpaired e's

Why are transition elements able to act as catalysts?

Since they can show different oxidation states

Why does Pt, Pd & Ni act as catalyst?

They have large surface area which provides area for the rn

Why are these elements able to form complexes?

Due to small size of ion, high charge of metal ion, availability of empty d orbitals

Interstitial compds?

Spaces in b/n atoms in metal lattice which are occupied by small atoms like C, N, H

interstitial compds are _________ compds

non-stoichiometric

Properties of interstitial compds

High MP, hard compds, retain their metallic conductivity, chemically inert

Alloys are

homogeneous substitutional solid soutions in which some of the metal atoms are replaced by other metals

Brass is made of

Cu & Zn

Bronze is made of

Cu & Tin

K2Cr2O7 is obtained from

Chromite ore when treated with Na2CO3 & O2 & heated

To convert chromate to dichromate,

acid is added

To convert dichromate to chromate,

base is added

color of (CrO4)2-

yellow

Color of (Cr2O7)2-

orange

Effect of H+ on CrO4?

It converts it to Cr2O7

Why does CrO4 show color despite having unpaired e's?

Due to charge transfer

How is KMnO4 obtained?

K2MnO4 when kept for some time or when treated with acid give KMnO4

Colour of (MnO4)2-

green

Why does H undergo reduction instead of K+ in KMnO4 formation?

Since K+ has -ve potential since it is a metal

One property of Kr2CrO7?

It is a good oxidising agent in all mediums

Why is silver a transition element?

d orbitals are completely filled in d^10s^2

Why is enthalpy of atomisation lowest for Zn in 3d series?

d orbitals are not involved in bonding, so metallic bond is weak and energy to break them to atoms is low

how +2 state becomes more stable in 1st half of 3d series with increasing atomic number?

the 3d orbitals get gradually occupied and empty orbitals decrease so stability increases from Sc2+ to Mn2+

characteristics of d block elements?

1. (n-1)d^1-10 ns^1-2 metallic lustre, high tensile strength, ductile, malleable 2. decrease in radius with increasing at. no 3. Increasing ionisation enthalpy from left to right 4. Increase in sum of 1st & 2nd ionisation enthalpies 5. They form complexes 6. They show dia & para magnetism 7. Form coloured ions 8. Used as catalysts

Transition elements have _______ electrical & thermal conductivity

high

Transition elements have ____ volatility

low

Transition elements have ______ MP

high

In what way is E.C of these elements different from non-transition elements?

In non-transition elements, d orbitals are absent or completely filled

Most common states by lanthanoids

2, 3 and 4

Why transition metals have high enthalpies of atomisation?

Due to large no of unpaired e's. These atoms have strong interatomic interaction & stronger bonding

Why do these elements form coloured compds?

Due to partial absorption of visible light. The e' absorbs the radiation of a particular freq & jumps to next orbital

How states differ in transition and non transition metals?

In non transition metals ,variation is selective ie they differ by 2 and states of transition elements differ by 1

Effect of increase in pH on K2Cr2O7

It changes to K2Cr2O4(orange to yellow)

Examples of disproportionation rns?

1. 3MnO4 + 4H --> 2MnO4 + MnO2 + 2H2O 2. 3CrO4 + 8H --> 2crO4 + Cr3+ + 4H2O

Example for lowest oxide is basic, highest oxide is acidic/amphoteric

MnO(Mn2+) ; Mn2O7(Mn7+)

Alloy which contains lanthanoid metals

mischmetal which has S, C, Ca & Al

Use of mischmetal

Produce bullets, shell & lighter flint

Elements of 1st series posess diff properties than those of heavier elements?

Due to larger atomic radii of heavier elements, high ionization and atomisation enthalpy, higher MP & BP

Ce exhibit

Pr exhibit

Tb exhibit

Nd exhibit

Sm & Eu exhibit

Electronic COnfig for lanthanoids

[Xe]4f^1-14 5d^0-1 6s^2

Electronic Config for actinoids

[Rn]5f^1-14 6d^0-1 7s^2

Most stable state for lanthanoid

+3. Some show 2 & 4

Most stable state for actinoids

Besides three, 4,5,6, & 7 are seen

Reactivity of lanthanoids

Less reactive metals

Reactivity of actinoids

More reactive

Which doesn't form oxocations?

Lanthanoids

Which forms complexed easily?

Actinoids

________ compds are less basic

lanthanoid

Which CuX2 will not be formed?

CuI2

As size of ion increases, its covalent nature

decreases

Why are Yb2+ & Eu2+ good reducing agents?

it will try to go to its stable +3 state and get oxidised

Why are Ce +4 & Tb 4+ good oxidising agents?

They show tendency to get reduced to +3 state to be stable

The only radioactive element in lanthanoids

Promethium(Pm)

Which has highest MP in lanthanoids?

Samarium(Sm) 1623K

Lanthanoids are good _______ agents

reducing

Lanthanoids have __ potential values

-ve

Most stable state in Lanthanoids

Why is +2 state also shown by lanthanoids?

Stable half or filled orbitals

Atomic size _____ with increase in atomic no. due to poor shielding effect

decrease

Basic strength of hydroxides of lanthanoids

Decreases from Ce to Lu

Why does covalent nature increase when size of ion decrease?

When size is less, +ve ion will have greater polarising power to capture the e' cloud of the anion due to which OH cannot be given easily(Fajan's rules). So basicity decreases.

Does lanthanides show color & paramagnetism?

Yes

lanthanoids have spin &

orbital magnetic moment

Lanthanoid + H2O gives

LnOH3 + H2(displaces H)

uses of Lanthanoids

1. Oxides are used as catalysts in cracking of petroleum 2. Oxide used to make Crook's lens for protection from UV rays 3. Making Mischmetal

Pyrophoric alloy

Mischmetal + magnesium

Why is pyrophoric alloy used for making bullets?

It catches fire easily

Actinoid contraction

Poor shielding effect of 5f e's

Why lanthanoids have greater ionisation energy than actinoids?

4f is near to nucleus than 5f so it can pull the e's more than those of 5f

Why does actinides show more oxidation states?

Less diff in energy b/n 5f 6d 7s

Mn2O7 is acidic where MnO is basic

Mn has +7 in Mn2O7 which is more acidic

Acidic nature increase on _____ in oxidation states

Increasing

d block elements exhibit more oxidatoin states than f block

Less energy diff b/n d & s orbitals in d block

Zr & Hf have similar atomic radii

Lanthanoid contraction

Titration of FeSO4 with KMnO4 uses dil H2SO4 & not dil HCl. Why?

Chlorine produces greenish yellow gas which interrupts pale pink colour needed.

Co2+ is easily oxidised in presence of strong ligands

Co 2+ will easily lose 1 e' to be stable

Transition elements have high enthalpy of atomisation. Why?

Due to strong metallic bonding due to unpaired e's