Advertisements
Advertisements
प्रश्न
NF3 is possible, but NF5 is not. Why?
Advertisements
उत्तर
According to the electronic configuration of nitrogen, it does not have 3d orbital that's why it can't expand the valency up to 5 and does not form .
N does not have vacant d orbitals. Hence, there is no excitation of ns2 electron to vacant orbitals. Thus, has only three unpaired electrons in p-orbitals showing +3 oxidation state and not +5 in halides like other elements of group.
APPEARS IN
संबंधित प्रश्न
Which metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
Calculate magnetic moment of `Fe_((aq))^(2+) ion (Z=26).`
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element shows only +3 oxidation state?
Why do the transition elements have higher enthalpies of atomisation?
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
For M2+/M and M3+/M2+ systems, the EΘ values for some metals are as follows:
| Cr2+/Cr | −0.9 V |
| Mn2+/Mn | −1.2 V |
| Fe2+/Fe | −0.4 V |
| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
Use this data to comment upon:
The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+.
How would you account for the following:
Cobalt (II) is stable in aqueous solutions, but in the presence of complexing reagents, it is easily oxidised.
Write the formula of an oxo-anion of Chromium (Cr) in which it shows the oxidation state equal to its group number
Why do transition elements show variable oxidation states ? In 3d series (Sc to Zn), which elements shows the maximum number of oxidation state and why ?
Two metallic elements A and B have the following standard oxidation potentials: A = 0·40v B = - 0·80v. What would you expect if element A was added to an aqueous salt solution of element B? Give a reason for your answer.
Explain why Zn2+ salts are white whereas Cu2+ salts are coloured.
Read the passage given below and answer the following question:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
Assertion: Transition metals form protective oxide films.
Reason: Oxides of transition metals are always stoichiometric.
Assertion: The highest oxidation state of osmium is +8.
Reason: Osmium is a 5d-block element.
Answer the following question:
Which element of the first transition series has highest second ionisation enthalpy?
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:
(activation energy, Threshold energy, increased, lowered, partially, full, d-d transition, Benzoic acid, benzaldehyde)
Only those transition metal ions will be coloured which have ______ filled d-orbitals facilitating ______.
A metallic ion 'M' reacts with chloride ion to form white precipitate which is readily soluble in aqueous ammonia. Identify 'M'?
Photographic film and plates have - au essential ingredient of
Sodium this sulphate is used in photography because of its:-
Agcl is soluble in NH4OH. The solubility is due to the information of:-
On adding NaOH, solution to the aqueous solution of K2CrO7 the colour of the solution changes from
Which of the following ions will exhibit colour in aqueous solution?
Why is the `"E"_(("V"^(3+)//"V"^(2+)))^"o"` value for vanadium comparatively low?
The oxidation state of Fe in [Fe(CO)5] is ______.
Which one among the following metals of the 3d series has the lowest melting point?
Account for the following:
Copper has an exceptionally positive `"E"_("M"^(2+)//"M")^0` value.
Explain the use of different transition metals as catalysts.
The compounds of \[\ce{Ti^4+}\] ions are colourless due to ______.
Give a reason for the following:
Transition metals possess a great tendency to form complex compounds.
A coordination compound has the formula \[\ce{CoCl3.4NH3}\]. It precipitates silver ions as AgCl and its molar conductance corresponds to a total of two ions.
Based on this information, answer the following question:
- Deduce the structural formula of the complex compound.
- Write the IUPAC name of the complex compound.
- Draw the geometrical isomers of the complex compound.
