Question

Give the name and formula of the compound formed from the following elements: (a) cesium and bromine; (b) sulfur and barium; (c) calcium and fluorine.

Answer 1

Answer: (a) cesium and bromine :$CsBr_2$

(b) sulfur and barium: $BaS$

(c) calcium and fluorine :$CaF_2$

Explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  

The nomenclature of ionic compounds is given by:

1. Positive is written first.

2. The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.

(a) cesium and bromine: Here cesium is having an oxidation state of +1 called as $Cs^{+}$ cation and bromine $Br^{-}$ is an anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral $CsBr$ called as cesium bromide.

(b) sulfur and barium : Here barium is having an oxidation state of +2 called as $Ba^{2+}$ cation and sulphur $S^{2-}$ is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral $BaS$. called as barium sulfide.

(c) calcium and fluorine: Here calcium is having an oxidation state of +2 called as $Ca^{2+}$ cation and fluorine $F^{-}$ is an anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral $CaF_2$. called as calcium fluoride.