Decide whether each pair of elements in the table below will form an ionic compound. If they will, write the empirical formula of the compound formed in the space provided.
| element #1 | element #2 | Forms ionic compound? | empirical formula of ionic compound |
|---|---|---|---|
| cesium | chlorine | yes | $\square$ |
| rubidium | bromine | yes | $\square$ |
| sulfur | strontium | yes | $\square$ |
| calcium | cesium | yes | $\square$
Answer (2)
Cesium and chlorine form CsCl.
Rubidium and bromine form RbBr.
Sulfur and strontium form SrS.
Calcium and cesium form Cs 2 Ca.
The empirical formulas are determined by balancing the charges of the ions. C s Cl , R b B r , S r S , C s 2 C a
Explanation
Problem Analysis We need to determine the empirical formulas for the ionic compounds formed by the given pairs of elements.
Cesium and Chlorine Cesium (Cs) forms Cs + ions, and chlorine (Cl) forms Cl − ions. To form a neutral compound, we need one Cs + and one Cl − ion. Therefore, the empirical formula is CsCl.
Rubidium and Bromine Rubidium (Rb) forms Rb + ions, and bromine (Br) forms Br − ions. To form a neutral compound, we need one Rb + and one Br − ion. Therefore, the empirical formula is RbBr.
Sulfur and Strontium Strontium (Sr) forms Sr 2 + ions, and sulfur (S) forms S 2 − ions. To form a neutral compound, we need one Sr 2 + and one S 2 − ion. Therefore, the empirical formula is SrS.
Calcium and Cesium Calcium (Ca) forms Ca 2 + ions, and cesium (Cs) forms Cs + ions. To form a neutral compound, we need one Ca 2 + ion and two Cs + ions to balance the charges. Therefore, the empirical formula is Cs 2 Ca.
Final Answer The empirical formulas for the ionic compounds are:
Cesium and chlorine: CsCl
Rubidium and bromine: RbBr
Sulfur and strontium: SrS
Calcium and cesium: Cs 2 Ca
Examples
Ionic compounds are used in various applications, such as table salt (NaCl), which is essential for human health and food preservation. Understanding how elements combine to form ionic compounds helps us predict the properties of new materials and design them for specific purposes, such as batteries, semiconductors, and catalysts. For example, the compound calcium fluoride (CaF 2 ) is used in the production of hydrofluoric acid and as a flux in metallurgy.
The pairs of elements will form ionic compounds with the following empirical formulas: CsCl for cesium and chlorine, RbBr for rubidium and bromine, SrS for sulfur and strontium, and Cs 2 Ca for calcium and cesium. This is based on the charge interactions between metals and nonmetals. Each formula is determined by balancing the positive and negative charges of the ions involved.
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