Question

Explain why the electron configuration for copper is \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{1} 3 d^{10}\) rather than the predicted \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{9}\).

Short answer

The electron configuration of copper prioritizes a full 3d sublevel for increased stability.

Step-by-step solution

Understand Electron Configuration

In simple terms, electron configuration refers to the distribution of electrons in an atom's orbitals. The orbitals are arranged in energy levels and sublevels (s, p, d, f), where electrons fill from lower energy levels to higher ones.

Identify the Predicted Electron Configuration

Copper (Cu), with an atomic number of 29, is expected to have its electrons fill the 4s and then the 3d sublevel based on the Aufbau principle, which suggests that electrons fill the 4s sublevel before the 3d. Thus, the predicted configuration is \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^9\].

Analyze the Actual Electron Configuration

The actual configuration of copper is \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}\]. Contrary to the filling order, the copper atom takes an electron from the 4s sublevel to fill the 3d sublevel completely.

Explain the Stability of Full and Half-Full Sublevels

In chemistry, fully filled or half-filled sublevels provide additional stability to the atom. By moving one electron from the 4s sublevel to fill the 3d sublevel completely, copper attains a more stable electron configuration.

Conclude the Reasoning

The adjustment in copper's electron configuration occurs to enhance stability as a full 3d sublevel holds lower energy and thus provides more stability than a partially filled sublevel.

Key concepts

Atomic Structure

Atoms are the building blocks of matter. They consist of a nucleus, composed of protons and neutrons, surrounded by electrons that move in specific regions called orbitals. The electron's location and movement are dictated by quantum mechanics.
- **Nucleus**: Contains protons, which are positively charged particles, and neutrons, which are neutral. They make up the majority of an atom's mass. - **Electrons**: Negatively charged particles that orbit the nucleus in various energy levels. These levels are organized into sublevels: s, p, d, and f. Each sublevel has a specific number of orbitals where electrons can reside. - **Orbitals and Energy Levels**: Electrons fill these from lower to higher energy. The arrangement and behavior of electrons in these orbitals form the basis of an atom's electron configuration, an essential aspect of understanding atomic structure.

Aufbau Principle

When determining electron configuration, the Aufbau principle guides us in understanding how electrons occupy orbitals. This principle states that electrons fill lower-energy orbitals first before moving to higher-energy ones.
- **Order of Filling**: Electrons fill the 1s orbital before the 2s, then 2p, and so on. This filling order minimizes energy within the atom. - **Exceptions to the Rule**: While the Aufbau principle gives a general idea, exceptions occur due to specific stability benefits. Typically, fully filled or half-filled orbitals provide enhanced stability due to electron-electron interactions and symmetric distribution. Understanding the Aufbau principle helps explain why certain atoms, like copper, might not adhere strictly to predicted configurations for achieving lower energy states.

Copper Electron Configuration

Copper is an interesting element because its electron configuration does not follow the predicted filling order. While we expect copper to fill its orbitals in the order determined by the Aufbau principle, copper surprises us with an unexpected configuration.
- **Predicted Configuration**: Based on the Aufbau principle, copper's configuration should be \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^9\).- **Actual Configuration**: The actual electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}\). Here, copper takes an electron from the 4s orbital to complete the 3d orbital.- **Stability Rationale**: A full d sublevel (\(3d^{10}\)) is more stable than a partially filled one. Stability arises from symmetrical electron distribution and lower electron repulsion.The odd configuration of copper underlies a foundational concept in chemistry: sometimes achieving a stable, lower energy state demands deviation from the norm. Copper's arrangement embodies this principle by prioritizing stability over strict adherence to energy-level filling orders.