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Chemistry : Quantum Mechanical Model of Atom

**26. Which quantum number reveal
information about the shape, energy, orientation and size of orbitals?**

**27. How many orbitals are possible
for n =4?**

**Answer:**

n = 4 *l*
= 0, 1, 2, 3

four sub-shells ⇒ s, p, d,
f

*l *= 0m* _{l}* = 0 ; one 4s orbital.

*l *= 1 m* _{l} *= –1, 0, +1 ; three 4p

*l *= 2 m* _{l} *= –2, –1, 0, +1, +2 ; five

*l *= 3 m* _{l} *= -3, –2, –1, 0, +1, +2 ,

Over all Sixteen orbitals.

**28. How many radial nodes for 2s,
4p, 5d and 4f orbitals exhibit? How many angular nodes?**

**Answer:**

**29. The stabilisation of a half
filled d - orbital is more pronounced than that of the p-orbital why?**

**30. Consider the following
electronic arrangements for the d ^{5} configuration.**

**(i) which of these represents the
ground state**

**(ii) which configuration has the
maximum exchange energy.**

**Answer:**

**31. State and explain pauli's exclusion
principle.**

**32. Define orbital? what are the n
and l values for 3p _{x} and 4d_{x}2_{-y}2 electron?**

**Answer:**

**33. Explain briefly the time
independent schrodinger wave equation?**

**34. Calculate the uncertainty in
position of an electron, if Δv = 0.1% and υ = 2.2 x10 ^{6} ms^{-1}**

**Answer:**

**35. Determine the values of all the
four quantum numbers of the 8th electron in O- atom and 15 ^{th}
electron in Cl atom and the last electron in chromium**

**Answer:**

**36. The quantum mechanical treatment
of the hydrogen atom gives the energy value:**

**i) use this expression to find ΔE
between n = 3 and m=4**

**ii) Calculate the wavelength
corresponding to the above transition.**

**Answer:**

**37. How fast must a 54g tennis ball
travel in order to have a de Broglie wavelength that is equal to that of a
photon of green light 5400Å?**

**Answer:**

**38. For each of the following, give
the sub level designation, the allowable m values and the number of orbitals**

**i) n = 4, l =2, ii) n =5, l = 3 iii)
n=7, l=0**

**Answer:**

**39. Give the electronic
configuration of Mn ^{2+} and Cr^{3+}**

**40. Describe the Aufbau principle**

**41. An atom of an element contains
35 electrons and 45 neutrons. Deduce**

**i) the number of protons**

**ii) the electronic configuration for
the element**

**iii) All the four quantum numbers
for the last electron**

**Answer:**

**42. Show that the circumference of
the Bohr orbit for the hydrogen atom is an integral multiple of the de Broglie
wave length associated with the electron revolving arround the nucleus.**

**43. Calculate the energy required
for the process.**

**He ^{+} _{(g)} → He^{2+}
_{(g)} + e^{-}**

**The ionisation energy for the H atom
in its ground state is - 13.6 ev atom ^{-1}.**

**Answer:**

**44. An ion with mass number 37
possesses unit negative charge. If the ion contains 11.1% more neutrons than
electrons. Find the symbol of the ion.**

**Answer:**

**45. The Li ^{2+} ion is a
hydrogen like ion that can be described by the Bohr model. Calculate the Bohr
radius of the third orbit and calculate the energy of an electron in 4^{th}
orbit.**

**Answer:**

**46. Protons can be accelerated in
particle accelerators. Calculate the wavelength (in Å) of such accelerated
proton moving at 2.85 ****×****10 ^{8} ms^{-1} ( the
mass of proton is 1.673 **

**Answer:**

**47. What is the de Broglie
wavelength (in cm) of a 160g cricket ball travelling at140 Km hr ^{-1}.**

**Answer:**

**48. Suppose that the uncertainty in
determining the position of an electron in an orbit is 0.6 Å. What is the
uncertainty in its momentum?**

**Answer:**

**49. Show that if the measurement of
the uncertainty in the location of the particle is equal to its de Broglie
wavelength, the minimum uncertainty in its velocity is equal to its velocity /
4π**

**Answer:**

**50. What is the de Broglie wave
length of an electron, which is accelerated from the rest, through a potential
difference of 100V?**

**Answer:**

**51. Identify the missing quantum
numbers and the sub energy level**

**Answer:**

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