Chapter 2, Problem 1SQ

An atom can be changed into an ion by adding or removing ___. An atom can be changed into a different isotope by adding or removing ____.

Summary Introduction

To determine:

The addition or removal of which sub-atomic particle can change an atom into an ion and an atom into a different isotope.

Introduction:

The atom is the smallest unit of biological organization. However, there are particles even smaller than an atom and such particles together make up the atom. These sub-atomic particles include protons, neutrons, and electrons. In the center of an atom, the nucleus is present. The nucleus is composed of protons (positively charged particles) and neutrons (neutral particles). Electrons (negatively charged particles) revolve around the nucleus in designated orbitals.

Answer to Problem 1SQ

Correct answer:

An atom can be changed into an ion by adding or removing electrons. An atom can be changed into a different isotope by adding or removing neutrons.

Explanation of Solution

An ion is a charged particle formed by the atoms to attain stability. Atoms can either form a positively charged ion called a cation or a negatively charged ion called an anion. Ions are formed by the change in the number of electrons. If electrons are lost, the positive charge on the atom increases. Thereby, an atom changes into a cation. If electrons are gained by the atom, the atom becomes negatively charged. Thereby, an atom changes into an anion. For example, the sodium ($\text{Na}$) atom loses an electron and forms a cation (${\text{Na}}^{+}$). An atom of chlorine ($\text{Cl}$) gains an electron to form an anion (${\text{Cl}}^{-}$).

Isotopes are variants of the same element but with different masses. The mass of an atom is contributed by the masses of protons and neutrons in the nucleus. If the number of protons is changed, the element will change. The change in the number of neutrons in the nucleus of an atom leads to the formation of an isotope. For example, the isotopes of hydrogen (zero neutrons) include protium (zero neutrons), deuterium (one neutron), and tritium (two neutrons).

Conclusion

The change in the number of electrons and neutrons leads to the formation of an ion and an isotope, respectively.