Question

give the noble gas electron configuration for the only cadmium ion (element 48). the possible ions are given on the periodic table above the symbol. recall that when forming ions elements tend to end up with completely full and completely empty subshells. _1_ 5_2_ 4_3_

Explanation:

Step1: Identify the noble - gas core

Cadmium (Cd) has an atomic number of 48. The nearest noble gas with a lower atomic number is krypton (Kr) which has an atomic number of 36. So the noble - gas core is [Kr].

Step2: Determine the remaining electrons

After using the krypton core, we have 48 - 36=12 electrons left to distribute.

Step3: Write the electron configuration of the remaining electrons

The electron configuration of the remaining electrons follows the Aufbau principle. The next sub - shells are 4d and 5s. The 5s sub - shell fills first and can hold 2 electrons, and the 4d sub - shell can hold 10 electrons. So the electron configuration of Cd is [Kr]5s²4d¹⁰. When cadmium forms an ion, it loses 2 electrons to form Cd²⁺. The 2 electrons are lost from the 5s orbital first. So the electron configuration of Cd²⁺ is [Kr]4d¹⁰.

Answer:

[Kr] 5s⁰ 4d¹⁰