d & f Block Flashcards
1
Q
General electronic configuration of transition elements is
A
(n−1)d1−10ns1−2
2
Q
Reason for lanthanoid contraction is
A
negligible screening effect of f-orbitals
3
Q
Chromyl chloride test confirms the presence of
A
Cl−
4
Q
Formula of Mohr’s Salt is
A
FeSO4 ( NH4)2 SO4 . 6H2O
5
Q
The outer electronic configuration of chromium is
A
4s1 3d5
6
Q
Electronic configuration of Gadolinium is
A
[Xe]4 f7 5d1 6s2
7
Q
in 3d series which element shows highest oxidation state
A
Mn
8
Q
Fe, Co , Ni are magnetic substance of which type
A
Ferromagnetic
9
Q
Number of unpaired electrons in Fe+2 ion is
A
4
10
Q
In which of the compounds Mn shows highest oxidation state
K2MnO4
KMnO4
MnO2
Mn3O4
A
KMnO4
11
Q
The atomic radius of Zr and Hf are similar due to
A
Lanthanide contraction
12
Q
Transition elements are coloured due to
A
Unpaired electron in d-orbital
13
Q
Stability of ferric ion is due to
A
Half filled d-orbital
14
Q
Inner transition element is :
Sc
Hg
V
Ce
A
Ce
15
Q
Metals Fe, Cu , Ni are known as__________
A
Ferrous metals
16
Q
Ionice size of trivalent cations ______ with increase in atomic numbers.
A
Decreases
17
Q
The transition metals having lower oxidation state show ____ nature
A
basic
18
Q
Zn shows only ____ oxidation state
A
+2
19
Q
f-block elements are known as _____ elements
A
Inner transition elements
20
Q
Transition elements and their compounds act as
A
Catalyst
21
Q
General electronic configuration of inner transition elements is
A
(n-2)f 0-14 ( n-1) d 0-1 ns2
22
Q
Colour of Ni 2+ is
A
Green
23
Q
Elements of 1st inner transition series are called
A
Lanthanides
24
Q
True/False
f-block elements are called inner transition elements
A
True
25
True/False
Transition elements and their compounds act as catalysts
True
26
True/False
Zn, Hg are generally considered as transition elements
False
27
True/False
Cu + ion is coloured
False
28
True/False
transition elements exhibit variable oxidation states
True
29
True/False
KMnO4 is a strong oxidising agent
True
30
Compounds of transition elements are generally colourless
False
31
Coin metals are :
Cu, Ag and Au
32
Maximum paramagnetism is shown by
Mn 2+
33
platinum metals :
The platinum group metals (PGMs) comprise 6 elements, which are platinum, palladium, rhodium, ruthenium, iridium, and osmium
34
Rare earth elements :
f-block elements
35
Zn 2+ is
| tell colour and magnetic substance
colourless and diamagnetic
36
____ metal is used for hydrogenation of oils
Ni
37
All _______ are radioactive
Actinides
38
Structure of XeF4 is
Square planar
39
Oxidation state of Mn
+7
In its compounds manganese exhibits oxidation states from +2 to +7. The common oxidation states are +2, +4, and +7, but the less common +3, +5, and +6 states are easily prepared
40
Which is colourless Cu2+ or Cu+ ?
Cu+
41
Write the electronic config. of Scandium .
Scandium (21) = [Ar] 3d¹ 4s²
42
Which oxidation state of lanthanum is most stable ?
+3
43
How many unpaired electrons are present in Fe3+
5
44
Out of d-block elements , Zn does not show variable valencies, why ?
because of completely filled d-orbitals
45
Which is the most important oxidation state of Cu ?
+2
46
f-block elements can be divided into how many series ?
2
47
What is "lunar caustic" ?
AgNo3 (silver nitrate)
48
In d-block elements Zn does not exhibit variable oxidation state why ?
due to fully filled d-orbitals
Due to lack of empty d-orbitals Zn does not show any electronic transitions, therefore no variable oxidation state is exhibited.
49
What is the alkaline soln of HgCl2 and KI known as
Nessler's reagent
50
The salts of transition metals are generally coloured, why ?
Due to d-d transition
51
Actinide contraction is greater from element to element than Lanthinide contraction , why ?
this is due to poor shielding effect by 5f electrons in actinoids than that of 4f electrons in the lanthanoids.
52
EXPLAIN WHY Cu+ IS COLOURLESS WHILE Cu2+ IS COLOURED
Cu+ has 3d10 configuration ( no d-d transition of electrons ) while Cu2+ ion has 3d9 configuration (d-d transition is possible ). As a result, Cu2+ is colourless and Cu2+ is coloured.
53
WHY ARE Mn 2+ COMPOUNDS MORE STABLE THAN Fe 2+ TOWARDS OXIDATION IN THEIR +3 OXIDATION STATE
Mn2+ COMPOUNDS ARE MORE STABLE DUE TO HALF-FILLED D-ORBITALS. Fe2+ COMPOUNDS ARE COMPARATIVELY LESS STABLE AS THEY HAVE SIX ELECTRONS IN THEIR 3 d-ORBITAL. SO, THEY TEND TO LOSE ONE ELECTRONS (FORM Fe3+) AND GET STABLE 3d5 CONFIGURATION.
54
WHAT ARE INTERSTITIAL COMPOUNDS ? WHY ARE SUCH COMPOUNDS WELL KNOWN FOR TRANSITION METALS ?
MOST OF THE TRANSITION ELEMENTS FOR INTERSTITIAL COMPOUNDS AT HIGH TEMPERATURE WITH ATOMS OF NON METALLIC ELEMENTS LIKE : H, B , C , Si ETC. SMALL ATOMS OF THESE NON-METALLIC ELEMENTS FIT IN THE INTERSTITIAL VOIDS OF CRYSTAL LATTICS OF TRANSITION ELEMENTS. THESE ARE CALLED INTERSTITIAL COMPOUNDS.
55
WHAT ARE ALLOYS ? NAME AN IMPORTANT ALLOW WHICH CONTAIN SOME OF THE LANTHANOID METALS. MENTION ITS USES
AN ALLOY IS A HOMOGENOUS MIXTURE OF TWO OR MORE METALS OR METALS AND NON METALS. AN IMPORTANT ALLOY CONTAINING LANTHANOID METAL IS MISCHMETAL WHICH CONTAINS 50% Cerium AND 25% Lanthanum WITH SMALL AMOUNTS OF Nd (Neodymium) AND Pr (Praseodymium). IT IS USED IN Mg BASED ALLOY TO PRODUCE BULLETS , SHELL AND LIGHTER FLINTS.
56
Ti 2+ , V 2+ AND Cr 2+ ARE STRONG REDUCING AGENTS , WHY ?
FOR Ti 2+ , V 2+ AND Cr 2+, VALUE OF M 2+ / M IS NEGATIVE WHICH JUSTIFIES THAT THEY ARE STRONGLY REDUCING
57
Zn SHOWS ONLY +2 OXIDATION STATE , WHY ?
BY LOSING TWO ELECTRONS Zn2+ FORMS A FULFILLED STABLE d10 ELECTRONIC CONFIGURATION. FURTHER REMOVAL OF ELECTRON FROM THIS FILLED d-ORBITAL REQUIRES VERY HIGH ENERGY. THEREFORE IT ONLY SHOWS + 2 OXIDATION STATE.
58
EXPLAIN WHY Cu+ ION IS NOT STABLE IN AQUEOUS SOLN
Cu + ION IS NOT STABLE IN AQUEOUS SOLN BECAUSE OF ITS LESS NEGATIVE ENTHALPY OF HYDRATION THAN Cu +2
59
WHAT IS LANTHANOID CONTRACTION AND WHAT ARE ITS CONSEQUENCES
The steady decrease in the size of lanthanide ions with the increase in atomic number is called lanthanide contraction.
Consequences:
There is not regular trend in ionization potential in the group due to lanthanide contraction.
Similarity of 2nd and 3rd transition group
60
WHAT ARE TRANSITION METALS ? THEY SHOW METALLIC CHARACTER , WHY ?
In general, any element which corresponds to the d-block of the modern periodic table (which consists of groups 3-12) is considered to be a transition element.
General Electronic config (n-1)d1-10 ns 1-2.
Transition elements show metallic character as they have low ionisation energies and have several vacant orbitals in their outermost shell. This property favours the formation of metallic bonds in the transition metals, and so they exhibit typical metallic properties. T
61
62
WHY DO TRANSITION METALS EXHIBIT VARIABLE VALENCIES?
BECAUSE THE ENERGY SUBSHELL (n-1)d & ns ARE VERY CLOSE. THUS POSSIBILITY TO LOSE ELECTRONS FROM ns subshell and (n-1)d SUBSHELL IS VERY MUCH IF THERE ARE UNPAIRED ELECTRONS. SO OXIDATION STATES OF THESE METALS MAY INCREASE.
Mn SHOWS MAXIMUM VARIABLE VALENCIES.
63
TRANSITION ELEMENTS FORM ALLOY EASILY , WHY ?
The atomic sizes of transition metals are relatively very similar to each other, which attributes to their nature of forming the alloys.
Due to this reason, the similar-sized metal can replace the other metal from its lattice and form a solid solution which is the alloy.
This also explains, why transition metals form homogeneous mixtures with one another or metals with non-metals in the molten state, which is also known as an alloy.
64
THE RADIUS OF Fe 3+ ION IS SMALLER THAN THAT OF Mn 3+ ION , WHY ?
Ionic radius of Fe2+ is less than that of Mn2+ because effective nuclear charge is more in Fe2+(Z=26) as compared to Mn2+(Z=25), remembering that d-electrons have pour screening effects.
65
transition metals posses the ablity to form complex compounds , explain
they have small size ions and high nuclear charge due to which they attract ligands
Transition metals generally form more complex or coordination compound because they have empty valence shell orbitals that can accept pair of an electron from lewis base (ligand) That means ligands must contain one pair (at least) of the non-bonding electron that can be donated to the metal ion.
66
WHY IS Ti KNOWN AS WONDER METAL ?
IT IS A SHINING WHITE METAL
IT IS STRONG ( HARDER THAN STEEL )
HAS HIGH M.P.
IT IS GOOD CONDUCTOR OF ELECTRIC CURRENT
DUE TO ALL THESE QUALITIES IT IS CALLED A WONDER METAL
67
TiO2 IS WHITE WHEREAS TiCL3 IS VIOLET, WHY ?
IN TiO2 , Ti IS IN +4 OXIDATION STATE , HAVING A VACANT d-ORBITAL HENCE THERE IS NO d-d TRANSITION AND ITS WHITE.
Ti IS IN +3 OXIDATION STATE HAVING ONE UNPAIRED ELECTRON IN ITS 3d-ORBITAL HENCE IT IS COLOURED.
68
IN FIRST TRANSITIONAL SERIES, PARAMAGNETISM INCREASES TILL Cr THEN IT STARTS DECREASING , WHY ?
First they are singly occupied which increases paramagnetism until the point where all the d-orbitals are half-filled (point of maximum paramagnetism) and then they get paired which decreases paramagnetism. Hence, paramagnetism first increases till maximum then decreases.
69
WHAT ARE INNER TRANSITION ELEMENTS
In the inner transition elements the third last shell is filled with electrons.
The inner transition elements form coloured ions.
The inner transition elements show variable valencies.
lanthanide: between cerium (Z=53) and lutetium (Z=71)
actinides starting with thorium (Z = 90) and ending with lawrencium (Z = 103).
70
WHAT IS CHROMYL CHLORIDE TEST
The chromyl chloride test is a qualitative analysis test used for the detection of Cl– ions
Chromyl chloride is a chemical compound, and its chemical formula is given as CrO2Cl2
Chromyl Chloride Test Mechanism
The mechanism of the chromyl chloride test is simple. On reacting potassium dichromate with sulphuric acid, chromate trioxide (oxidation state = +6) is formed. The colour of chromate trioxide (CrO3) varies from dark red to brown colour.
K2Cr2O7 + H2SO4 → CrO3 + H2O
Now, the salt-containing chloride (NaCl) is reacted with sulphuric acid that gives sodium bisulphate (NaHSO4), and hydrochloric acid (HCl) is also formed.
NaCl +H2SO4 → NaHSO4 +HCl
In the next step, chromate trioxide is reacted with hydrochloric acid, which produces chromyl chloride (CrO2Cl2 ), which gives out red fumes.
CrO3 + HCl → CrO2Cl2
Confirmation for Chromyl Chloride Test
Now, for the confirmation of chromyl chloride, the red vapour needs to dissolve in a solution of sodium hydroxide (NaOH). The solution turns yellow (due to Na2CrO4).
CrO2Cl2 + NaOH → Na2CrO4 + NaCl +H2O
Reacting this solution further with the lead acetate and diluted acetic acid (CH3COOH) produces the yellow precipitate.
CrO42- + Pb(CH3COO)2 → PbCrO4 +CH3COONa
PbCrO4 is the yellow precipitate of chloride, and hence the test is accurate.
71
COLOUR OF
Cr 4+
BLUE
72
COLOUR OF Mn 2+
VIOLET
73
COLOUR OF Fe 2+
GREEN
74
COLOUR OF Ni 2+
GREEN
75
COLOUR OF Cr 3+
VIOLET
76
COLOUR OF Mn 3+
PINK
77
COLOUR OF FE 3+
YELLOW
78
DIFFERENCE B/W LANTHANOIDS AND ACTINOIDS
LANTANIDES:
Last electron enters into a 4f orbital.
General electronic configuration 4f[0-14]5d[0-1] 6s2
The decrease in atomic size is not regular as the decrease in size of tripositive ions (Ln3+) is regular.
The principal and common oxidation state is +3. Some elements also show +2 and +4 oxidation states.
They do not form complexes readily.
Their compounds are less basic.
These elements are non-radioactive except promethium.
Actinoids:
Last electron enters into a 5f orbital.
General electronic configuration 5f[1-14]6d[0-1] 7s2
There is a gradual decrease in the atomic and ionic (tripositive ion) size.
The common oxidation state is +3 but it is not always the stable state. The elements in the first half of the series frequently show higher oxidation states for example, the maximum oxidation state increases from +4 in Th to +5, +6 and +7 in Pa, U and Np respectively.
They have much greater tendency to form complexes.
Their compounds are more basic.
They are all radioactive.
