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 sub-atomic particles whose addition or subtraction can give rise to an ion and an isotope.

Introduction:

The atom is the smallest unit of biological organization. However, there are particles even smaller than an atom and that together make up the atom. These sub-atomic particles include protons, neutrons, and electrons. In the center of an atom, the nucleus is present, which 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 and it forms a cation. If electrons are gained by the atom, the atom gets negatively charged and forms an anion. For example, the sodium ( $\text{Na}$) atom loses an electron to get stabilized and form a positive cation ( ${\text{Na}}^{+}$). An atom of chlorine ( $\text{Cl}$) gains an electron to form a negatively charged chloride anion ( ${\text{Cl}}^{-}$).

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

Conclusion

To form an ion, the number of electrons is supposed to be changed and to form an isotope, the number of neutrons is supposed to change.