Chapter 7, Problem 55A

Interpretation Introduction

Interpretation: The reason for cation to have a positive charge needs to be explained.

Concept Introduction: Ions are formed when an atom of element gains or loses electron/s. An atom gains or loses electrons to attain noble gas electron configuration or to complete its octet.

Answer to Problem 55A

A cation is a positive charge because the number of electrons present in it is less than the number of electrons present in its neutral atom.

Explanation of Solution

Cations are positive charge ions that are formed when an atom loses electrons. These electrons are valence electrons of an atom. An atom is composed of protons, neutrons, and electrons. Here, the proton is a positive charge, a neutron is neutral, and the electron is a negative charge. In a neutral atom, the number of protons and electrons is equal; thus, the charge on the atom is zero.

When an atom loses electron/s, the number of electrons decreases but the number of protons remains the same. Since electrons are a negative charge and protons are a positive charge, the positive charge on the atom increases. Thus, a cation has a positive charge because the number of electrons present in it is less than the number of electrons present in its neutral atom.

Conclusion

Thus, the charge on an ion depends on the number of electrons. If the number of electrons is more as compared to the number of electrons in the neutral atom, the ion will have a negative charge and if the number of electrons is less it will have a positive charge.