Electronic configuration of calcium

General
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electronic configuration of calcium

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What is the electronic configuration of calcium?

Answer: The electronic configuration of calcium can be understood by examining its position in the periodic table and applying the principles of electron distribution in atomic orbitals.

Calcium (Ca) is an element with the atomic number 20. This means it has 20 protons and, in a neutral atom, 20 electrons. The electronic configuration describes the arrangement of these electrons in the atom’s orbitals.

Steps to Determine the Electronic Configuration:

  1. Identify the Total Number of Electrons:

    • Calcium has 20 electrons.

  2. Follow the Aufbau Principle:

    • Electrons fill orbitals starting from the lowest energy level to the highest. The order of filling is based on the increasing energy levels of orbitals.

  3. Apply the Pauli Exclusion Principle and Hund’s Rule:

    • Each orbital can hold a maximum of 2 electrons with opposite spins (Pauli Exclusion Principle).
    • Electrons will fill degenerate orbitals (orbitals of the same energy) singly first before pairing up (Hund’s Rule).

Filling the Orbitals:

  1. 1s Orbital:

    • Can hold up to 2 electrons.
    • Configuration: 1s^2

  2. 2s Orbital:

    • Can hold up to 2 electrons.
    • Configuration: 2s^2

  3. 2p Orbitals:

    • Can hold up to 6 electrons.
    • Configuration: 2p^6

  4. 3s Orbital:

    • Can hold up to 2 electrons.
    • Configuration: 3s^2

  5. 3p Orbitals:

    • Can hold up to 6 electrons.
    • Configuration: 3p^6

  6. 4s Orbital:

    • Can hold up to 2 electrons.
    • Configuration: 4s^2

When we sum up the electrons in these orbitals, we get:

$$1s^2 + 2s^2 + 2p^6 + 3s^2 + 3p^6 + 4s^2 = 20 \text{ electrons}$$

Thus, the electronic configuration of calcium (Ca) is:

\mathbf{1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2}

Noble Gas Notation:

For simplicity, the electronic configuration can also be represented using the noble gas notation. The nearest noble gas preceding calcium is argon (Ar), which has the configuration [Ar]. Therefore, the configuration of calcium can be written as:

\mathbf{[Ar] \, 4s^2}

This notation shows that calcium has the same electron configuration as argon, plus two additional electrons in the 4s orbital.

Conclusion:

The electronic configuration of calcium is 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 or, in noble gas notation, [Ar] \, 4s^2. This configuration explains the chemical properties of calcium, including its reactivity and its position in Group 2 (alkaline earth metals) of the periodic table.