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Predict the ground-state electron configuration of the following ions. Write your answers in abbreviated form, that is, beginning with a noble gas in brackets.a). Cr2+b.)Cu2+c.)Co3+

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These are three questions and three complete answers

Answer:

a) Cr²⁺: [Ar] 4s² 3d²

b) Cu²⁺: [Ar] 4s² 3d⁷

c) Co³⁺: [Ar] 4s² 3d⁴

Explanation:

a) Cr²⁺

  • Z = 24
  • Number of protons: 24
  • Number of elecrons of the neutral atom: 24
  • Charge of the ions: + 2
  • Number of electrons of the ion: 24 - charge = 24 - 2 = 22.
  • Electron configuration:

       Fill the orbitals in increasing order of energy. Using Aufbau's rules the order is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ .....

       Hence, for 22 electrons you get:

       1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²

  • Abbreviated notation: since the last complete level is the number 3s² 3p⁶, you use the noble gas of the period 3, which is Ar, and the configuration is:

       

        [Ar] 4s² 3d²

b) Cu²⁺

  • Z = 29
  • Number of protons: 29
  • Number of elecrons of the neutral atom: 29
  • Charge of the ion: + 2
  • Number of electrons of the ion: 29 - charge = 29 - 2 = 27.
  • Electron configuration:

       Fill the orbitals in increasing order of energy. Using Aufbau's rules the order is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ .....

       Hence, for 27 electrons you get:

       1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷

  • Abbreviated notation: since the last complete level is the number 3s² 3p⁶, you use the noble gas of the period 3, which is Ar, and the configuration is:

       

        [Ar] 4s² 3d⁷

c) Co³⁺

  • Z = 27
  • Number of protons: 27
  • Number of elecrons of the neutral atom: 27
  • Charge of the ion: + 3
  • Number of electrons of the ion: 27 - charge = 27 - 3 = 24.
  • Electron configuration:

       Fill the orbitals in increasing order of energy. Using Aufbau's rules the order is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ .....

       Hence, for 24 electrons you get:

       1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴

  • Abbreviated notation: since the last complete level is the number 3s² 3p⁶, you use the noble gas of the period 3, which is Ar, and the configuration is:

       

        [Ar] 4s² 3d⁴