What Is the Magnetic Moment Formula for Transition Elements? D and F Block Elements, Chemistry Class 12

TL;DR

The magnetic moment formula in chemistry is μeff = √[n(n + 2)] Bohr magnetons, where n is the number of unpaired electrons in an atom or ion. Electron configurations give n: Fe3+ has five unpaired electrons and a magnetic moment of 5.91 μB, while Co2+ has three and 3.87 μB. Read on to see how these values are calculated.

Transcript

click the Bell icon to get latest videos from equator helpers in the previous topic we have discussed about the catalytic activity of the transition metals and now in this topic we are going to talk about the magnetic moment for the transition metals and now in this topic let us understand what is the formula behind the effective magnetic moment as... Read More

Key Insights

• 🤘 Transition metals have a magnetic moment, which is primarily due to the spin motion of the electrons.
• 🫚 The effective magnetic moment is calculated using the formula square root of (n + 2) Bohr magneton, where n represents the number of unpaired electrons.
• #️⃣ The number of unpaired electrons can be determined by analyzing the electron configuration.
• 😑 The effective magnetic moment can be used to determine the paramagnetic or ferromagnetic nature of a compound or ion.
• 😑 The value of the effective magnetic moment can vary between different transition metal ions.
• 😑 The effective magnetic moment of Fe3+ ion is 5.91 μB, indicating its paramagnetic nature.
• 😑 The effective magnetic moment of Co2+ ion is 3.87 μB, indicating its paramagnetic nature but with a lower value compared to Fe3+ ion.

Questions & Answers

Q: What is the magnetic moment formula in chemistry?

The effective magnetic moment formula is μeff = √[n(n + 2)] Bohr magnetons. Here, n represents the number of unpaired electrons in the atom or ion.

Q: What causes the magnetic moment of transition elements?

Electron orbital motion and spin motion both contribute to magnetic moment. The transcript identifies electron spin as the main source of the effective magnetic moment.

Q: How is the number of unpaired electrons found for a transition metal ion?

First write the electron configuration of the neutral atom, then remove the required electrons to obtain the ion. Draw the occupied d orbitals and count the electrons that remain unpaired.

Q: How is the electron configuration of Fe3+ determined?

Neutral iron has atomic number 26 and the configuration [Ar] 4s2 3d6. For Fe3+, two electrons are removed from 4s first and one from 3d, producing [Ar] 4s0 3d5.

Q: What is the effective magnetic moment of Fe3+?

Fe3+ has five unpaired electrons, so n = 5. Substitution into √[n(n + 2)] gives √35, or 5.91 μB.

Q: How is the electron configuration of Co2+ determined?

Cobalt has atomic number 27 and the neutral configuration [Ar] 4s2 3d7. Removing the two 4s electrons gives Co2+ the configuration [Ar] 4s0 3d7.

Q: What is the effective magnetic moment of Co2+?

The 3d7 configuration of Co2+ has three unpaired electrons, so n = 3. The formula gives √15, or 3.87 μB.

Q: What do the magnetic moments of Fe3+ and Co2+ indicate?

The calculated values indicate that Fe3+ and Co2+ are paramagnetic. Fe3+ has the larger effective magnetic moment, 5.91 μB compared with 3.87 μB for Co2+.

Summary & Key Takeaways

• Transition metals have electrons that revolve around the nucleus, which gives them a magnetic moment.

• The magnetic moment is mainly due to the spin motion of the electrons.

• The effective magnetic moment can be calculated using the formula square root of (n + 2) Bohr magneton, where n represents the number of unpaired electrons in the atom or ion.