Chemistry Notes 2nd Year Chap 6

                                                      Important Questions

Q1 Give the general properties of transition elements.

Ans: Because of a smaller electronic configuration m the d-block elements resemble one another in their physical and chemical properties. Some of the points of their resemblance are given below.

      They are all metal in true sense. Some of which play important role in industry like Tr,Cr,Mn, Fe W etc.

     They are hard and strong metals with high melting point and boiling point. They are good conductor of electricity and heat.

     They forms alloy with one another and with other elements.

They show variable oxidation state.

Their ions ans compounds are colourd in solid state as well as in solution from at least in one if not all the oxidation state.

Q2 What are chelates ? Give examples.

Ans: When the polydetale ligand surrounds the central metal atom or ion cyclic coordination complex ion is produced called chelates .

 Q3 What is tin planting and what happen when it is damag.

Ans: The process of tin planting consists dipping the clean sheet of iron in a bath of molten tin and then passing the sheet trough hot pair of rollers. Such plates are used in the manufacture of tin canes oil canes and other smaller articles. tin itself is stable and protect the metal effectively as long as it is intact with the metal.

If the tin planting is damaged then the iron sheet is corroded more rapidly than un-plated sheet,it is because the iron comes in contact with the moisture and galvanic cell is established. In the galvanic cell the iron act as anode and tin as cathode. Electrons flow from iron to tin where they discharge the H+ ions leaving OH-1 behind which combine with the iron forming Fe(OH)3 which dissolve rapidly in water.

Q4 What are the interstitial compounds ? 

Ans: When small nonmetallic atoms like H,B,C,N enter the interstices metals and impart useful features to them they are called the interstitial compounds. They are non-stoichiometric compounds also known as  the interstitial alloys.

Q5 Discuss d&f block elements why they are called transition elements.

Ans: The elements having partially filled with (n-1) d orbital are called d-block elements.

The elements having partially filled with (n-2) f orbital are called f block elements.

d-block and f0block elements are present in between the s&p block elements in the modern periodic table. Their properties are in between  the s&p block elements varying from left to right. Since their properties show a systematic transitional phase from metallic to non metallic behavior therefore thery are called transition elements.

 Q6 How it is indicated that reaction occuring in Bessemer's process has subsided ? Why Ferromanganese is added ?

Ans: Completion of reaction in the Bessemer's process indicated when blue flame of CO subsided which shows that the carbon is completely oxidized. At this stage ferromanganese is added to correct the propertion of carbon to obtain the desired qualities.

Q7 Explain d-d transition. Why transition metal compounds are coloured ?

Ans: In transition metals the d orbitals are responsible for colour development in their compounds. When these orbitals are involved in bonding they split in two sets one higher energy and other is lower energy. the electron residing is lower d orbitals absorb energy of visible light and jump to higher d orbital. This process is call d-d block transition. The energy difference d orbital varies from ion to ion. Thus every ion absorbs a different wavelenght and transmits the remaining set of wavelenght that gives different colours to the ions.

Q8 Write formulas chromat and dichromate ions.

Potassium dichromate has the composition K2Cr2O7 and is of orange red color.

Potassium chromate has the composition K2CrO4 and is yellow color.

Q9 What is difference between paramagnetic and dimaganetic substances ?

Ans: Substances which are weakly attracted by strong magnetic field are called paramagnetic substances. It is due to presence of unpaired electron.

                        Substances which are weakly repelled by strong magnetic field are called dimagnetic substances. It is due to presence of paired electrons.

Q10 Differentiate between the inner and outer transition elements.

Ans: The transition elements having partially filled (n-1) d orbital are called outer transition elements. They include the d block elements.

                      The transition elements having partially filled (n-2) f orbital are called inner transition elements. They include the f block elements.

Q11 What are typical and non-typical transition elements and why they are called SO?

Ans: These are elements which possess partially filled (n-1) d orbital in their atomic state or commonly occurring oxidation state are called typical transition elements e.g members of II-B & III-B groups.

These are elements which possess partially filled (n-2) f in their atomic state or commonly occurring oxidation state are called non-typical transition elements e.g members of IV-B,V-B,VII-B&VIII-B groups.

Q12 What are Co-ordination number ,Central metal atom  Co-ordination sphere ligands.

Ans: Co-ordination number:

                                               The number of electron pair accepted by the metal atom from the ligands is called Co-ordination number.

Central Metal Atom: 

                                    Metal atom or ion member of d or f block which accepted electron pair from ligands is called central metal atom.

  Co-ordination Sphere: \

                                      The space enclosed in the square bracket containing all the ligand and central metal atom or ion is call Co-ordination sphere.

Ligand: 

             An atom or group of atoms may be neutral postive or negative charge which can donate electron pair to the central metal is called the ligand.