Question

Which ionic compound is expected to form from combining the following pairs of elements: (a) barium and fluorine, (b) cesium and chlorine, (c) lithium and nitrogen, (d) aluminum and oxygen?

Short answer

The ionic compounds formed by combining the given pairs of elements are: (a) Barium Fluoride: \(BaF_2\) (b) Cesium Chloride: \(CsCl\) (c) Lithium Nitride: \(Li_3N\) (d) Aluminum Oxide: \(Al_2O_3\)

Step-by-step solution

(Step 1: Determine the charge of each ion)

Using the periodic table, we can determine the charge of each ion in the given pairs of elements. For example, metals in Group 1 have a charge of +1, metals in Group 2 have a charge of +2, and nonmetals in Group 17 have a charge of -1.

(a) Barium and Fluorine)

Barium (Ba) is a Group 2 element, so its ion has a charge of +2 (Ba^2+). Fluorine (F) is a Group 17 element, so its ion has a charge of -1 (F^-).

(b) Cesium and Chlorine)

Cesium (Cs) is a Group 1 element, so its ion has a charge of +1 (Cs^+). Chlorine (Cl) is a Group 17 element, so its ion has a charge of -1 (Cl^-).

(c) Lithium and Nitrogen)

Lithium (Li) is a Group 1 element, so its ion has a charge of +1 (Li^+). Nitrogen (N) is a Group 15 element, so its ion has a charge of -3 (N^3-).

(d) Aluminum and Oxygen)

Aluminum (Al) is a Group 13 element, so its ion has a charge of +3 (Al^3+). Oxygen (O) is a Group 16 element, so its ion has a charge of -2 (O^2-).

(Step 2: Combine the ions to form ionic compounds)

Now that we have the charges, we can combine each pair of elements in a way that their overall charge is neutral, forming the ionic compound.

(a) Barium and Fluorine)

To achieve a neutral charge, we need two fluorine ions for each barium ion: \[Ba^{2+} + 2F^{-} \rightarrow BaF_2\]

(b) Cesium and Chlorine)

To achieve a neutral charge, we need one chlorine ion for each cesium ion: \[Cs^{+} + Cl^{-} \rightarrow CsCl\]

(c) Lithium and Nitrogen)

To achieve a neutral charge, we need three lithium ions for each nitrogen ion: \[3Li^{+} + N^{3-} \rightarrow Li_3N\]

(d) Aluminum and Oxygen)

To achieve a neutral charge, we need two aluminum ions for each three oxygen ions: \[2Al^{3+} + 3O^{2-} \rightarrow Al_2O_3\] So, the ionic compounds formed by combining the given pairs of elements are: (a) Barium Fluoride: \(BaF_2\) (b) Cesium Chloride: \(CsCl\) (c) Lithium Nitride: \(Li_3N\) (d) Aluminum Oxide: \(Al_2O_3\)