Determine the chemical formula for the ionic compound that forms between cesium and bromine.
The correct answer and explanation is :
The chemical formula for the ionic compound that forms between cesium (Cs) and bromine (Br) is CsBr.
Explanation:
Cesium (Cs) is an alkali metal, and bromine (Br) is a halogen. When cesium and bromine react, they form an ionic bond due to their significant difference in electronegativity. Here’s the detailed reasoning:
- Ionization of Cesium:
Cesium is located in Group 1 of the periodic table, which means it has one electron in its outermost electron shell. Cesium tends to lose this electron easily because it is very far from the nucleus, making it weakly bound. When cesium loses an electron, it forms a positively charged ion (cation):
[
\text{Cs} \rightarrow \text{Cs}^+ + e^-
]
This ion is written as Cs⁺. - Formation of Bromine Ion:
Bromine is a halogen in Group 17 and has seven electrons in its outermost shell. To achieve a stable electron configuration (similar to that of noble gases), bromine needs one more electron. Since it is highly electronegative, bromine readily accepts an electron from another atom, forming a negatively charged ion (anion):
[
\text{Br} + e^- \rightarrow \text{Br}^-
]
The bromine ion is written as Br⁻. - Ionic Bond Formation:
The cesium ion (Cs⁺) and the bromine ion (Br⁻) are oppositely charged. Opposite charges attract, which leads to the formation of an ionic bond between them. The resulting compound is electrically neutral because the positive charge of the Cs⁺ ion balances the negative charge of the Br⁻ ion. - Empirical Formula:
Since one cesium ion (Cs⁺) combines with one bromine ion (Br⁻) to form a neutral compound, the simplest ratio of cesium to bromine is 1:1. Therefore, the formula of the ionic compound is CsBr.
This ionic compound is known as cesium bromide. It is a white crystalline solid and forms through the transfer of an electron from cesium to bromine, creating ions that are held together by electrostatic forces in a crystal lattice.