We can represent atoms by listing the number of protons, neutrons, and electrons—for example, 2p+,2n0,2e− for helium. Which of the following represents the 18O isotope of oxygen?a. 7p+,2n0,9e−b. 8p+,10n0,8e−c. 9p+,9n0,9e−d. 10p+,8n0,9e-

Atoms are the basic units of matter, consisting of protons, neutrons, and electrons. Protons are positively charged particles found in the nucleus, neutrons are neutral particles also in the nucleus, and electrons are negatively charged particles that orbit the nucleus. The number of protons defines the element, while the number of neutrons can vary, leading to different isotopes of the same element.

Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This difference in neutron count results in varying atomic masses. For example, oxygen has several isotopes, including 16O and 18O, where 18O has two more neutrons than the more common 16O isotope.

The notation for isotopes typically includes the element symbol followed by the mass number, which is the sum of protons and neutrons. For instance, 18O indicates an oxygen isotope with a total of 18 nucleons (protons + neutrons). Understanding this notation is crucial for identifying isotopes based on their proton and neutron counts.