What is the electron configuration for a calcium atom? 1s2, 2s2, 2p6, 3s2, 3p6, 4s2 1s2, 2s2, 2p6, 3s2, 3p6, 4s1 2s2, 2s2, 2p6, 3s2, 3p6, 4s1 1s1, 2s2, 2p6, 3s2, 3p6, 4s1
The Correct Answer and Explanation is:
The correct electron configuration for a calcium atom is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Explanation:
1. Atomic Structure of Calcium:
Calcium (Ca) is a chemical element with the atomic number 20, meaning it has 20 protons in its nucleus. In a neutral atom, the number of electrons is equal to the number of protons. Therefore, a neutral calcium atom also has 20 electrons.
2. Electron Shells and Orbitals:
Electrons occupy specific energy levels, or shells, around the nucleus. The shells are denoted by principal quantum numbers (n), where n = 1, 2, 3, etc. Each shell contains subshells (s, p, d, f) that can hold a maximum number of electrons. The distribution of electrons among these shells and subshells is defined by the Aufbau principle, Hund’s rule, and the Pauli exclusion principle.
3. Filling Order of Electrons:
According to the Aufbau principle, electrons fill the lowest energy orbitals first. The order of filling orbitals is as follows:
- 1s can hold 2 electrons: 1s²
- 2s can hold 2 electrons: 2s²
- 2p can hold 6 electrons: 2p⁶
- 3s can hold 2 electrons: 3s²
- 3p can hold 6 electrons: 3p⁶
- 4s can hold 2 electrons: 4s²
After filling the 3p orbital, the next available orbital is 4s, which has a lower energy than 3d. Hence, the 4s subshell is filled before 3d.
4. Final Configuration:
After filling the orbitals in the order described, the electron configuration for calcium is completed as:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
This configuration indicates that the first shell has 2 electrons, the second shell has 8 electrons, the third shell has 8 electrons, and the fourth shell has 2 electrons, making up the total of 20 electrons present in a neutral calcium atom.
In summary, the electron configuration of calcium reflects its position in the periodic table and its chemical properties, including its tendency to lose two electrons to achieve a stable electron configuration similar to that of noble gases.