To reach a noble gas electron configuration how many electrons would selenium have to adopt

To reach a noble gas electron configuration how many electrons would selenium have to adopt? To reach a noble gas electron configuration how many electrons would selenium have to adopt? 1 6 2 10

The correct answer and explanation is:

Correct Answer: 2

Selenium (Se) has an atomic number of 34, meaning it has 34 electrons in its neutral state. The electron configuration of selenium is:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴

Selenium belongs to Group 16 in the periodic table and has six valence electrons in its outermost shell, specifically in the 4s² 4p⁴ orbitals. To reach a stable noble gas configuration, selenium needs to have a full outer electron shell. The nearest noble gas with a full shell is krypton (Kr), which has 36 electrons.

In order to achieve the same electron configuration as krypton, selenium must gain 2 electrons. This will fill its 4p orbital, giving it the stable configuration of:

4s² 3d¹⁰ 4p⁶

Once the 4p orbital is full, selenium will have the same outer electron arrangement as krypton. This makes selenium more stable, as atoms tend to gain, lose, or share electrons to complete their outermost energy level, following what is called the “octet rule.”

This rule states that atoms are generally most stable when they have eight electrons in their valence shell. Selenium, with six valence electrons, needs two more to make eight. By adopting or gaining two electrons, selenium forms a 2− ion (Se²⁻), which is common in many of its chemical compounds.

In conclusion, selenium would need to adopt 2 electrons to reach the noble gas configuration of krypton, becoming more chemically stable in the process.