Orbitals: Shapes, Energies, and Electron Configuration (up to Z=36)

A set of Q&A style flashcards covering orbital shapes, energies, degeneracy, quantum numbers, Hund's rule, Aufbau principle, electron configurations (up to Z=36), and related concepts.

What term describes orbitals within the same subshell that have the same energy?

Degenerate orbitals.

Which principle explains that electrons fill the lowest-energy orbitals first in atoms?

Aufbau principle (building-up principle).

What principle states that no two electrons can have the same four quantum numbers?

Pauli exclusion principle.

List the four quantum numbers used to describe an electron in an orbital.

n (principal), l (azimuthal), ml (magnetic), ms (spin).

What is the maximum value of the spin quantum number m_s for an electron?

±1/2 (two possible spin states).

What is meant by degenerate orbitals in a given subshell?

Orbitals that have the same energy within that subshell.

What is the ground-state electron configuration of oxygen (Z = 8)?

1s^2 2s^2 2p^4.

How many electrons can each of the first three shells (K, L, M) hold in total?

K holds 2, L holds 8, M holds 18 (2n^2 rule).

According to Hund's rule, how are electrons arranged in degenerate orbitals before pairing?

Place one electron in each degenerate orbital before pairing any two electrons in the same orbital.

In the 2p subshell with four electrons, how are the electrons distributed among the three 2p orbitals?

Two orbitals have one electron each; one orbital has two electrons (↑, ↑, ↑↓); two unpaired electrons total.

Which subshell is higher in energy within the same principal shell: 2s or 2p?

2p is higher energy than 2s.

What is the correct energy ordering of 3s, 3p, and 3d in many-electron atoms?

3s < 3p < 3d (with 4s able to lie below 3d due to energy overlap in some cases).

Which orbital fills before 3d due to energy ordering in the Aufbau process?

4s (before 3d).

What happens when an electron is excited and then relaxes, in terms of light emission?

Light is emitted with energy equal to the difference in energy between the higher and lower energy states.

What are the four blocks of the periodic table defined by electron configuration?

s-block, p-block, d-block, f-block; each block corresponds to the last subshell being filled.

Why did Bohr's model fail for multi-electron atoms?

It did not account for electron–electron interactions and shielding, leading to non-degenerate subshell energies.