The Oxygen Family element, Selenium (Se) has a valence number of , and an oxidation number of .

The Valence and Oxidation Numbers of Selenium

1. Understanding Valence Number

   • The valence number refers to the number of electrons an atom can lose, gain, or share during a chemical reaction.

2. Selenium’s Valence Electrons

   • Selenium (Se) is in Group 16 of the periodic table, also known as the Oxygen family. Its electron configuration is $[Ar] 3d^{10} 4s^{2} 4p^{4}$.
   • Selenium has six valence electrons: $4s^2 4p^4$.

3. Establishing Oxidation States

   • Selenium can exhibit multiple oxidation states, the most common being $-2$, $+4$, and $+6$.
   • The $-2$ oxidation state occurs when selenium gains two electrons to achieve a noble gas configuration (similar to krypton).

Final Answer

• Valence Number of Selenium (Se): 6
• Common Oxidation Numbers of Selenium (Se): -2, +4, +6