Question

what is the element that corresponds to the electron configuration $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2$?

• k
• ca
• sc
• sr

Explanation:

Step1: Calculate total electrons

Sum the exponents in the electron configuration: \(2 + 2 + 6 + 2 + 6 + 2 = 20\).

Step2: Identify element by atomic number

The atomic number equals the number of electrons (for a neutral atom). The element with atomic number 20 is Calcium (Ca).

Answer:

B. Ca