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dexar [7]
3 years ago
14

How many of the following elements have 2 unpaired electrons in the ground state? C Te Hf Si

Chemistry
1 answer:
AleksAgata [21]3 years ago
5 0

Answer:

  • Option C) 3.

  • C, Te, and Si have two unpaired electrons in the ground state.

Explanation:

You must draw the electron configuration.

<u><em>C (carbon)</em></u>

  • Atomic number (Z): 12
  • Number of electrons: 12
  • Electron configuration of ground state, following Aufbau rules (filling orbitals in order of increasing energy):

        1s² 2s² 2p²

  • Electron pairing following Hund's rules (fill different orbitals of same energy, with same spin, before adding a second electron, with opposite spin, to an orgital).

        1s² 2s² 2px↑ 2py↑

  • As you see, these configuration shows two unpaired electrons (same spin) in the ground state.

<u><em>Te (tellurium)</em></u>

  • Z = 52
  • Number of electrons: 52
  • Aufbau's rule and short notation: [Kr] 5s² 4d¹⁰ 5p⁴
  • Hund's rule:  [Kr] 5s² 4d¹⁰ 5px↑↓ 5py↑ 5pz↑
  • This configuration shows two unpaired elecctrons (same spin).

<u><em>Hf (hafnium)</em></u>

<u><em></em></u>

  • Z = 72
  • Number of electrons: 72
  • Aufbau's rule and short notation: [Xe] 4f¹⁴ 5d²6s²
  • This configuration shows that there are not unpaired electrons (the las orbital 6s is complete with 2 electrons)

<u><em>Si (silicon)</em></u>

<u><em></em></u>

  • Z = 14
  • Number of electrons: 14
  • Aufbau's rule and short notation: [Ne] 3s² 3p²
  • Hund's rule: [Ne] 3s² 3px↑ 3py↑
  • This configuration shows two unpaired electrons.

Conclusion: C, Te and Si, have two unpaired electrons (same spin) in the ground state.

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