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Structure of Atom question

2023 · 25 Jan · Shift 2 · Q18
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Structure of Atom question

2023 · 25 Jan · Shift 2 · Q18

JEE MainChemistryStructure of AtomNumerical+4 / −1
The number of given orbitals which have electron density along the axis is ‾\underline{\hspace{2cm}}​ px,py,pz,dxy,dyz,dxz,dz2,dx2−y2\mathrm{p_x,p_y,p_z,d_{xy},d_{yz},d_{xz},d_{z^2},d_{x^2-y^2}}px​,py​,pz​,dxy​,dyz​,dxz​,dz2​,dx2−y2​
Numerical answer
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Correct answer: 5

  1. We need to count how many of the listed orbitals have electron density along an axis.

  2. The given orbitals are: px,  py,  pz,  dxy,  dyz,  dxz,  dz2,  dx2−y2p_x,\; p_y,\; p_z,\; d_{xy},\; d_{yz},\; d_{xz},\; d_{z^2},\; d_{x^2-y^2}px​,py​,pz​,dxy​,dyz​,dxz​,dz2​,dx2−y2​

  3. Recall the orientations:

  • pxp_xpx​ has its lobes along the xxx-axis Rightarrow RightarrowRightarrow electron density along an axis.
  • pyp_ypy​ has its lobes along the yyy-axis Rightarrow RightarrowRightarrow electron density along an axis.
  • pzp_zpz​ has its lobes along the zzz-axis Rightarrow RightarrowRightarrow electron density along an axis.

So all three ppp orbitals qualify.

  1. Now the ddd orbitals:
  • dxyd_{xy}dxy​ has lobes between the xxx and yyy axes, not along any axis.
  • dyzd_{yz}dyz​ has lobes between the yyy and zzz axes, not along any axis.
  • dxzd_{xz}dxz​ has lobes between the xxx and zzz axes, not along any axis.
  • dx2−y2d_{x^2-y^2}dx2−y2​ has lobes along the xxx- and yyy-axes Rightarrow RightarrowRightarrow electron density along axes.
  • dz2d_{z^2}dz2​ has two lobes along the zzz-axis (and a torus in the xyxyxy-plane) Rightarrow RightarrowRightarrow electron density along an axis.

Thus, among the ddd orbitals, only dz2d_{z^2}dz2​ and dx2−y2d_{x^2-y^2}dx2−y2​ qualify.

  1. Total count: 3+2=53 + 2 = 53+2=5

  2. Therefore, the number of orbitals having electron density along the axis is: 5\boxed{5}5​

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