Question

module 4: electrons in atoms test - 11/14/2025
which of the following includes the name, symbol, and atomic number of the element represented by the noble - gas notation kr5s¹?
○ krypton (kr), 36.
○ rubidium (rb), 37.
○ yttrium (y), 39.
○ strontium (sr), 38

Explanation:

Noble - gas notation \([Kr]5s^{1}\) means we start with the electron configuration of krypton (\(Kr\), atomic number \(36\)) and then add one more electron in the \(5s\) orbital. The atomic number of the element is \(36 + 1=37\). Rubidium (\(Rb\)) has an atomic number of \(37\). Krypton (\(Kr\)) has an atomic number of \(36\) and is just the noble - gas core here. Yttrium (\(Y\)) has an atomic number of \(39\) and its electron configuration starts with \([Kr]4d^{1}5s^{2}\). Strontium (\(Sr\)) has an atomic number of \(38\) and its electron configuration starts with \([Kr]5s^{2}\).

Answer:

Rubidium (Rb), 37.