Final answer:
The full electron configuration for calcium (Ca) is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s², fitting the Aufbau principle where electrons fill up orbitals starting from the lowest energy levels.Therefore, the correct answer from the given options is A. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
Step-by-step explanation:
The student asked for the full electron configuration for calcium (Ca), which is a chemical element with the atomic number 20. The correct full electron configuration of calcium (Ca) is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s². This configuration tells us how electrons are distributed in calcium's atomic orbitals.
Electrons occupy the lowest energy levels first, as indicated by the Aufbau principle. Since calcium is in the second column of the s block, its configuration ends with the 4s² sublevel being fully filled.
According to this principle, calcium's electrons fill the 1s, 2s, 2p, 3s, 3p orbitals completely before filling the 4s orbital. Therefore, the correct answer from the given options is A. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².