An unknown element is a nonmetal and has a valence electron configuration of \(n s^{2} n p^{4}\). a. How many valence electrons does this element have? b. What are some possible identities for this element? c. What is the formula of the compound(s) this element would form with lithium? hydrogen? magnesium? aluminum? fluorine?

The electron configuration of the element is \(n s^{2} n p^{4}\), where 'n' represents the energy level of the valence electrons. Since the element has 2 electrons in the s-subshell and 4 electrons in the p-subshell, the total number of valence electrons is 2 + 4 = 6.

The given valence electron configuration fits a non-metal element with 6 valence electrons in Group 16 of the periodic table. The elements in this group are Chalcogens: oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). The possibilities for the unknown element are sulfur, selenium, or tellurium, as oxygen is not typically presented with the electron configuration \(n s^{2} n p^{4}\), but rather with \(ns^{2} np^{2}\), and polonium is a metalloid.

1. With Lithium (Li): Lithium is an alkali metal that has one valence electron and typically forms a +1 ion. The unknown non-metallic element has a -2 ion charge due to its 6 valence electrons. Therefore, the formula for the compound would be Li₂X (where 'X' represents the unknown element). 2. With Hydrogen (H): Hydrogen forms a +1 ion. Since the unknown element has a -2 charge, the compound formed would be H₂X. 3. With Magnesium (Mg): Magnesium is an alkaline earth metal that has two valence electrons and forms a +2 ion. As the unknown element has a -2 charge, the compound formed would be MgX. 4. With Aluminum (Al): Aluminum is a metal with three valence electrons and forms a +3 ion. To balance the charges, two aluminum ions would need to bond with three ions of the unknown element. The formula for the compound would be Al₂X₃. 5. With Fluorine (F): Fluorine is a halogen that has seven valence electrons and forms a -1 ion. Since the unknown element has a -2 charge, we would need two fluorine ions for every one unknown element ion. The formula for the compound would be XF₂.