Question

Part A

If the following elements were involved in redox reactions, which noble-gas configuration would they most likely attain?

Drag the appropriate elements to their respective bins.

Elements: Be, Na, N, P, Sc, As, Rb
Bins: He, Ne, Ar, Kr

Part B

An unknown element, X, reacts with lithium to form the compound Li2X. In other compounds this element also can accommodate up to 12 electrons rather than the usual octet. What element could X be?

a. Mg

b. O

c. Cl

d. Po

Answer 1

Be - He

Na – Ne

N – Ne

P- Ar

Sc- Ar

As Kr

Rb- Kr

The Be2+ ion has 2 electrons, just like He. The ions Na+ and N3− each have 10 electrons like Ne. The P3− and Sc3+ each have 18 electrons like Ar. The ions As3− and Rb+ each have 36 electrons like Kr.

An unknown element, X, reacts with lithium to form the compound Li2X. In other compounds this element also can accommodate up to 12 electrons rather than the usual octet. What element could X be?

a. Mg

b. O

c. Cl

d. Po

The formula is Li2X, so the charge on the X anion must be 2-

the ion is X2- elements in group 6A form monatomic ions with a 2- charge. In your list that is O or Po

Because both form O2- and Po2-