Question

which of the following is the electron configuration for calcium, ca? a) $1s^22s^22p^63s^23p^64s^2$ b) $1s^22s^2$ c) $1s^22s^22p^63s^2$ d) $1s^22s^22p^63s^23p^6$ e) $1s^22s^22p^6$

Explanation:

Calcium (Ca) has an atomic number of 20, meaning it has 20 electrons. The electron configuration follows the Aufbau principle, filling orbitals in order of increasing energy: \(1s\), \(2s\), \(2p\), \(3s\), \(3p\), \(4s\), etc.

• Option a: \(1s^22s^22p^63s^23p^64s^2\) sums to \(2 + 2+ 6 + 2 + 6 + 2 = 20\) electrons, matching Ca's electron count.
• Option b: \(1s^22s^2\) has 4 electrons (Be), incorrect.
• Option c: \(1s^22s^22p^63s^2\) has 12 electrons (Mg), incorrect.
• Option d: \(1s^22s^22p^63s^23p^6\) has 18 electrons (Ar), incorrect.
• Option e: \(1s^22s^22p^6\) has 10 electrons (Ne), incorrect.

Answer:

a) \(1s^22s^22p^63s^23p^64s^2\)