d and f block Flashcards
The elements belonging to
groups 3 to 12 are called
d-block or transition elements
what are f-block elements
The f-block consists of elements in which 4 f and 5 f orbitals are progressively filled. also called as inner transition metals
The general electronic configuration of
transition elements is
(n-1)d(1-10) ns (0 1 2)
There are mainly four series of the transition metals which are?
3d series (Sc to Zn), 4d series (Y to Cd), 5d series (Laand Hf to Hg) and 6d series which has Ac and elements from Rf to Cn
The two series of the inner transition
metals are?
The two series of the inner transition
metals; 4f (Ce to Lu) and 5f (Th to Lr) are known as lanthanoids and actinoids respectively
which elements of group 12 have full d
10 configuration not regarded as transition metals
zinc cadmium and mercury
the expectation element of 3d series are
copper and chromium
both metallic and covalent bonding is present in the atoms of transition elements. why?
The metallic bonding is due to possession of one or two electrons and The presence of unpaired and unfilled d-orbitals favours covalent bonding.
Greater the number of unpaired d electrons, greater the number of covalent
bonds and therefore, greater is the strength of these bonds
facts
why are metals like Cr Mo and W very hard and metals like Zn Cd and Hg very soft
Greater the number of unpaired d electrons, greater the number of covalent bonds and therefore, greater is the strength of these bonds thats why s. Cr,
Mo and W are very hard metals as they have maximum number of unpaired d-orbitals while Zn, Cd and Hg are softer in nature as they do not have any unpaired d-orbitals.
In the first transition series, the atomic
radius gradually decreases from _____ to ______but from _______ to _____, it is nearly the same.
scandium to chromium but from chromium to copper
The decrease in atomic radii in each series, in the beginning,
is due?
to an increase in nuclear charge from member to member which tends to pull the ns electrons inward, i.e., it tends to
reduce the size
why is there no change in atomic radii in mid way of the series?
there are operating two effects namely screening effect and nuclear charge effect which oppose each other. In the
midway onwards of the series both these effects become nearly equal and thus, there is no change in atomic radii inspite
of the fact that atomic number increases gradually.
why is there an increase in atomic radii at the end of the series
This is due to electron-electron repulsions among (n - 1)d electrons. These repulsions become predominant at
the end of each series and thus size increases.
the transition metals of third
series except the fIrst member, lanthanum, have nearly the same radii as metals of second transition series above them. This is due to?
Lanthanide contraction
vertical row, the atomic radii is expected to ________ from top to bottom. T
increase
the ionic radii generally ______ as
the atomic number increases in a particular transition series
decreases
The ionic radii________ with increase of charge on the ion
decreases
all the transition elements except __ ,_____and ___ possess density higher than 5 g mL -1
scandium, yttrium and titanium
The two elements ___and___ have high densities
osmium and iridium
_______ has the highest melting point
Tungsten
the melting points of transition elements ______ on increasing atomic number
decrease
The smaller the value of total energy change for a particular oxidation state in aqueous solution, greater will be the stability of that oxidation state.
facts
which element doesn liberate hydrogen from dilute acids
copper(only reacts with oxidizing acids like h2so4 and hno3) and chromium(due to form of cr2o3 oxide)
the highest oxidation compounds are found in ____ and ____ elements
oxygen and fluorine
The variable oxidation states of a transition metal is due to?
the involvement of (n- 1)d and, outer ns electrons
the highest oxidation state increases with increase of atomic number, reaching to a maximum in the middle and then starts decreasing
facts
The highest oxidation state shown
by any transition metal is ________
+8. shown by Ruthenium in second
transition series and osmium in the third transition
The highest oxidation state shown
by first transition metal is ________
manganese
the minimum oxidation state sown y a
transition metal is equal to the number of _________electrons. expect _____ metal
ns electrons,,scandium
The colour of transition metal
ions arises from?
the excitation of electrons from the d-orbitals of lower energy to the d-orbitals of higher energy
when is colour NOT possible in transition metals
The transition metal ions which have completely filled d-orbitals OR empty d orbitals
what is paramagnetic substance
one which is weakly attracted into a magnetic field
what is diamagnetic substance
a diamagnetic substance is one which is repelled by a magnetic field.
when does paramagnetic substance arise
The paramagnetic behaviour arises due to the presence of one or more singly occupied atomic orbitals
when does diamagnetic substance arise
diamagnetic behaviour is due to presence of paired electrons in the atomic orbitals
The ability for formation of complexes falls on account of following three
reasons which are?
(i) Small size (ii) high nuclear charge (iii) a number of vacant orbitals of equivalent energy
The effective total magnetic moment is given by the formula
Ueff = .root(n + 2) B.M (where n is the number of unpaired electrons)
explain Catalytic property of the compounds of d block
Catalytic property is probably due to the utilisation of (n -1 )d-orbitals
nature of oxides in d bloc
(i) The oxides in lower oxidation states are basic in nature.
(ii) The oxides in intermediate oxidation states are
amphoteric.
(iii) The oxides of higher oxidation states are acidic in nature.
Chromium compounds in ___oxidation
states are strong oxidising agents.
+6
how is potassium dichromate formed
The hot saturated solution of sodium dichromate is mixed with KCl. Sodium chloride precipitates out from the hot solution which is filtered off. On cooling the mother liquor, crystals of potassium dichromate separate out.
how is chromium formed?
step 1; mix with excess sodium carbonate
step 2; heat with air in furance (sodium chromate. is formed)
step 3; add h2so4 to convert sodium chromate into dichromate
step 4; heat with co2 and add water
step 5; Reduction of Cr203 is done by Goldsmith alumino-thermic
process.(addition of al )
potassium dichormate on On heating with alkalies is converted to chromate,, what is
the colour changes
the colour changes from orange to yellow
On acidifying potassium dichormate what is
the colour changes
yellow colour changes to orange.
acidic solution, .of potassium dichormate ________ ions are present
dichromate ions are present.n .
In alkaline solution,of potassium dichormate ________ ions are present
chromate
explain Chromyl chloride test
This is a test of chloride. When a mixture of a metal chloride and potassium dichromate
is heated with conc. H2S04, orange-red vapours of chromyl chloride are evolved.
potassium dichormate oxidises ethyl alcohol to acetaldehyde and acetaldehyde
to acetic acid.
facts
Acidified KZCr207 solution reacts with hydrogen peroxide to give a ____ colored solution due to formation of _____
deep blue,,,,CrO5
Powdered K2Cr207 on treatment with warm concentrated HCI .
petigot’s salt.
Potassium dichromate on heating with carbon is reduced
to
potassium chromite
When potassium dichromate and ammonium chloride
mixture is heated,_______ is evolved.
nitrogen
what chemical is used find out whether a person is drunken or not
Acidified solution of K2Cr2O7 provides a test to find out whether a person is drunken or not A person is asked to breathe into a solution of K2Cr207 (acidified). If the colour
of the solution turns green, it confirms that the person is in drunken state
how is potassium permagnate formed
prepared by fusing pyrolusite ore either with KOH or K2C03 in presence
of atmospheric oxygen or any other oxidising agent such as KN03The fused mass is extracted with water. The solution is now treated with a current of chlorine or ozone or carbon dioxide to convert manganate into permanganate
what is the color of potassium permagnate
purple coloured crystalline compound
reaction potassium permagnate In alkaline solution
Colour changes first from purple to green and fmally becomes colourless. However, brownish precipitate is formed
reaction potassium permagnate In neutral solution
: Mn02 is formed. Brownish ppt. is present.
reaction potassium permagnate In acidic solution
In acidic solution (in presence of dilute H2S04): Manganous sulphate is formed. The solution becomes colourless
how will Fe Ni and Co react carbon monoxide
All the three metals, combine with carbon monoxide to form volatile carbonyls
Mohr’s salt
(NH4)2 SO4·FeSO4·6H20
Ferrous compounds are usually_______ ferric Compounds
green while
what is called green vitriol
ferrous sulphate
how is green vitriol prepared
green vitroil is prepared by
- dissolving iron scraps in sulfuric acid and addition of alcohol
OR
- ) It can also be prepared in the laboratory from the Kipp’s waste. The excess of sulphuric acid is neutralised by heating
with a small quantity of iron fillings. The solution is then crystallised
OR
formed by the oxidation of pyrites under the air and moisture
how is mohrs salt prepared
The double salt is best prepared by making
saturated solutions of pure ferrous sulphate and pure ammonium
sulphate in air free distilled water Both the solutions are mixed and allowed to cool Generally, few drops of sulphuric acid and a little iron wire are added before crystallisation the salt obtaine dis in green colour
cu(II) salts are generally which color?
bluish or greenish
ag(III) salt slats are generally which color?
yellowish
cu(I) and ag (II) salts are in whic color
colourless cuz as they have (n-1)d10 configuration
why is cu , au and ag unreactive
sublimation energy and ionisation potential
have very high values and thus, coinage metals are less reactive.
