Question

What is the electron configuration of \(\mathrm{Ca}^{2+}\) ? What is the electron configuration of \(\mathrm{Ti}^{2+}\) ?

Short answer

- For \\(\mathrm{Ca}^{2+}\\), the electron configuration is \\(1s^2 2s^2 2p^6 3s^2 3p^6\\). - For \\(\mathrm{Ti}^{2+}\\), it is \\(1s^2 2s^2 2p^6 3s^2 3p^6 3d^2\\).

Step-by-step solution

Understand Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. We generally follow the Aufbau principle, Hund's rule, and the Pauli exclusion principle to write it.

Write Electron Configuration for Neutral Ca

Calcium (Ca) has an atomic number of 20. The electron configuration for neutral Ca is written as follows using the Aufbau principle: \[ \mathrm{Ca}: 1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^2. \]

Adjust for \\(\mathrm{Ca}^{2+}\\)

When Ca loses two electrons to become \(\mathrm{Ca}^{2+}\), these electrons are removed from the outermost orbital, which is the 4s orbital. Thus:\[ \mathrm{Ca}^{2+}: 1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6. \]

Write Electron Configuration for Neutral Ti

Titanium (Ti) has an atomic number of 22. The electron configuration for neutral Ti is:\[ \mathrm{Ti}: 1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^2\ 3d^2. \]

Adjust for \\(\mathrm{Ti}^{2+}\\)

When Ti loses two electrons to become \(\mathrm{Ti}^{2+}\), these electrons are typically removed from the outermost 4s orbital first, then the 3d orbital. Thus:\[ \mathrm{Ti}^{2+}: 1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 3d^2. \]

Key concepts

Calcium ion

Calcium (Ca) is a chemical element that plays a significant role in many biological reactions, such as muscle contraction and neurotransmitter release. In its neutral state, calcium has 20 electrons. However, when calcium forms a calcium ion (\(\mathrm{Ca}^{2+}\)), it loses two electrons.

• These electrons are removed from the outermost electron shell, specifically from the 4s orbital.

This gives the calcium ion a more stable, noble gas electron configuration, resembling that of argon. The electron configuration of \(\mathrm{Ca}^{2+}\) is therefore:\[\mathrm{1s^2\,2s^2\,2p^6\,3s^2\,3p^6}\]This configuration not only achieves stability but also minimizes energy.

Titanium ion

Titanium (Ti) usually finds applications in aerospace due to its strength, lightweight, and resistance to corrosion. In a neutral state, titanium has 22 electrons. When it forms a titanium ion (\(\mathrm{Ti}^{2+}\)), it loses two electrons.

• For \(\mathrm{Ti}^{2+}\), electrons are typically removed starting from the 4s orbital before the 3d orbital.
• This is important because it keeps the underlying 3d orbitals intact.

Thus, the electron configuration for \(\mathrm{Ti}^{2+}\) is:\[\mathrm{1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,3d^2}\]Titanium ions like \(\mathrm{Ti}^{2+}\) often participate in catalytic roles due to the presence of partially filled d orbitals.

atomic orbitals

Understanding atomic orbitals is crucial for electron configuration. An atomic orbital is a region around the nucleus of an atom where electrons are likely to be found. Each atomic orbital can hold a specific number of electrons, up to two per orbital, with opposite spins.

• Atomic orbitals include s, p, d, and f types, with varying shapes and energy levels.
• The 's' orbitals are spherical, while 'p' orbitals have a dumbbell shape.

The concept of atomic orbitals is foundational when discussing electron configurations, as it helps determine how electrons are distributed in space around the nucleus. It's essential to understand these for working with ions or neutral atoms.

Aufbau principle

The Aufbau principle is a key rule in determining the electron configuration of an atom. This principle states that electrons will fill lower energy orbitals before moving to higher energy orbitals.

• This means that the 1s orbital is filled before the 2s orbital, and so on.
• It allows for constructing electron configurations by "building up" from the lowest energy level.

Understanding and applying the Aufbau principle is critical because it accurately predicts the arrangement of electrons in neutral atoms. The principle works in conjunction with principles like Pauli's exclusion principle and Hund's rule for precise configuration of electrons. These rules help ensure that the configurations minimize energy and remain stable.