Question

Which element is depicted by the following electron configuration?

Model of an atom with 2 electrons on the inner ring, 8 electrons on the 2nd ring, and 1 electron on the outer ring.

A. Boron, B, atomic number 5, mass number 11
B. Magnesium, Mg, atomic number 12, mass number 24
C. Potassium, K, atomic number 19, mass number 39
D. Sodium, Na, atomic number 11, mass number 23

Answer 1

The electron configuration with 2 electrons in the inner ring, 8 in the second ring, and 1 in the outer ring corresponds to sodium (Na), with atomic number 11 and mass number 23.

Step-by-step explanation:

The element depicted by the electron configuration of 2 electrons on the inner ring, 8 electrons on the second ring, and 1 electron on the outer ring is sodium (Na, atomic number 11, mass number 23).

An element's electron configuration can be determined by the distribution of its electrons among the different energy levels (or shells) and subshells. Sodium has a total of 11 electrons.

It fills the first energy level with 2 electrons (1s), the second level with 8 electrons (2s and 2p), and, crucially, it has 1 electron in the outermost level, the 3s subshell.

This matches the electron configuration represented by [Ne]3s¹, after the noble gas neon ([Ne]), revealing the underlying full shells.