1. Calcium's Electron Configuration
* Calcium (Ca) has an atomic number of 20, meaning it has 20 protons and 20 electrons.
* Its electron configuration is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
2. Losing Valence Electrons
* Calcium is in group 2 of the periodic table, which means it has two valence electrons (the electrons in the outermost shell, the 4s orbital in this case).
* When calcium loses these two valence electrons, it becomes a positively charged ion (cation).
3. Calcium Ion's Electron Configuration
* The calcium ion (Ca²⁺) now has 18 electrons.
* Its electron configuration becomes: 1s² 2s² 2p⁶ 3s² 3p⁶
4. Resemblance to Argon
* Notice that the electron configuration of Ca²⁺ is exactly the same as the electron configuration of the noble gas Argon (Ar), which also has 18 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶
Conclusion
When a calcium atom loses its two valence electrons, the resulting calcium ion (Ca²⁺) has an electron configuration that is the same as that of the noble gas Argon (Ar). This is a common phenomenon among elements, especially those in the first two groups and the last group (the halogens) of the periodic table. They tend to gain or lose electrons to achieve a stable electron configuration like that of a noble gas.
