Lesson 3-4: Electron Configuration using Orbital Orientation and Electron Magnetic Property

What does the term "Aufbau" mean, and in what language?

“Build up,” from the German word Aufbeen.

What does the Aufbau principle dictate?

Electrons occupy orbitals of lower energy before occupying higher energy orbitals.

On what are the filling orders of orbitals based according to the Aufbau principle?

Principal energy levels and sublevels.

What does the Pauli Exclusion Principle state?

A maximum of two electrons, each with opposite spins, can occupy a single atomic orbital.

Who proposed the Pauli Exclusion Principle and when?

Wolfgang Pauli, Austrian physicist, in the early 20th century (1900–1958)

What does Hund’s Rule of Maximum Multiplicity state?

Every orbital in a subshell is singly occupied before any orbital is doubly occupied.

According to Hund’s Rule, how must single electrons be arranged in equal-energy orbitals?

They must occupy each orbital singly with the same spin before pairing up with opposite spins.

What would happen if the electrons in the 1s orbital had parallel spins, and what was actually observed?

If the electrons in the 1s orbitals had parallel spins, their net magnetic fields should strengthen each other. But experimental results showed that the helium atom in its ground state has no net magnetic field. This observation supports the pairing of two electrons with opposite spins in the 1s orbital.

What is an orbital diagram?

consists of boxes and arrows that represents the orbitals and the electrons respectively. Each box is labeled with the principal quantum number and sublevel associated with the orbital

What provides direct evidence for specific electronic configurations of elements?

Measurements of magnetic properties.

What are paramagnetic materials?

Substances with unpaired electrons or spins, attracted by a magnet.

What are diamagnetic materials?

Substances with paired electrons (opposite spins), repelled by a magnet.

How does the number of electrons relate to magnetism?

Atoms with an odd number of electrons usually have unpaired spins and are paramagnetic.

Why is helium diamagnetic even though it has 2 electrons?

Its two electrons in the 1s orbital are paired with opposite spins, canceling out magnetic fields.

What did the experiment with helium’s magnetic field prove?

Electrons in the same orbital must have opposite spins (supporting Pauli’s Exclusion Principle).

Why is lithium paramagnetic?

It has an unpaired electron.

What tool shows whether an element is paramagnetic or diamagnetic?

The orbital diagram.

What orbital diagram feature characterizes paramagnetic substances?

They have unpaired electrons in orbitals.

Why are paramagnetic substances attracted to a magnetic field?

Unpaired electrons produce net magnetic moments that align with the external magnetic field.

Give an example of a paramagnetic substance.

Oxygen (O₂).

What orbital diagram feature characterizes diamagnetic substances?

All electrons are paired in orbitals.

Why are diamagnetic substances weakly repelled by a magnetic field?

They have no unpaired electrons, so no permanent magnetic moment.

Give an example of a diamagnetic substance.

Helium (He: 1s²).

What orbital diagram feature characterizes ferromagnetic substances?

They have unpaired electrons whose spins align parallel with each other spontaneously in a solid.

Why do ferromagnetic substances show very strong magnetism?

Strong exchange interactions cause unpaired spins to align, producing permanent magnetism stronger than paramagnetism.

Give examples of ferromagnetic elements.

Iron (Fe), Cobalt (Co), Nickel (Ni).