Question

The element oxygen has three naturally occurring isotopes, with $8,9,$ and 10 neutrons in the nucleus, respectively. (a) Write the full chemical symbols for these three isotopes. (b) Describe the similarities and differences between the three kinds of atoms of oxygen.

Short answer

The chemical symbols for the three naturally occurring oxygen isotopes with 8, 9, and 10 neutrons are ${}_8^{16}\text{O}$, ${}_8^{17}\text{O}$, and ${}_8^{18}\text{O}$, respectively. All three isotopes have the same chemical properties due to having 8 protons and 8 electrons, giving them the same basic chemical behavior. The main difference between the isotopes is the number of neutrons in the nucleus, resulting in different atomic mass numbers and slightly different physical properties like density and stability.

Step-by-step solution

Determine the number of protons in an oxygen atom

Oxygen has an atomic number of 8, which means it has 8 protons in its nucleus.

Calculate the mass number for each isotope and write their chemical symbols

To find the mass number, add the number of protons and the respective neutrons for each isotope: - Isotope 1: $8(protons)+8(neutrons)=16$ (\text{mass number}) - Isotope 2: $8(protons)+9(neutrons)=17$ (\text{mass number}) - Isotope 3: $8(protons)+10(neutrons)=18$ (\text{mass number}) Using the mass numbers and chemical notation, the chemical symbols for these three isotopes are: - Isotope 1: ${}_8^{16}\text{O}$ - Isotope 2: ${}_8^{17}\text{O}$ - Isotope 3: ${}_8^{18}\text{O}$

Describe the similarities between the oxygen isotopes

All three isotopes are oxygen atoms, which means they have the same chemical properties and react similarly. They all have 8 protons and 8 electrons, ensuring the same basic chemical behavior for each isotope.

Describe the differences between the oxygen isotopes

The main difference between these isotopes is the number of neutrons in the nucleus. Isotope 1 has 8 neutrons, isotope 2 has 9 neutrons, and isotope 3 has 10 neutrons. This difference in neutrons affects the mass of the atom and results in different atomic mass numbers. The isotopes might have slightly different physical properties, such as density and stability, due to the difference in atomic mass.

Key concepts

Isotope Notation

Isotope notation is a method used to specify the identity of an atom's isotope by denoting both the atomic number and the mass number in its chemical symbol. For oxygen, with the atomic number 8, the isotopes are written as \text{Isotope 1: }${}_8^{16}\text{O}$, \text{Isotope 2: }${}_8^{17}\text{O}$, and \text{Isotope 3: }${}_8^{18}\text{O}$. The lower left subscript represents the atomic number, and the upper left superscript represents the mass number. This system allows scientists and students to quickly identify the number of protons and the total count of protons plus neutrons in the nucleus of the atom, essential information for understanding an atom's properties.

Atomic Number

The atomic number of an element is the number of protons in the nucleus of an atom, it defines the element's identity. For example, all oxygen atoms have 8 protons, so the atomic number of oxygen is 8. This is denoted as the lower subscript in isotope notation, as seen in the oxygen isotopes \text{Isotope 1: }${}_8^{16}\text{O}$, \text{Isotope 2: }${}_8^{17}\text{O}$, and \text{Isotope 3: }${}_8^{18}\text{O}$. Regardless of the number of neutrons, if an atom has 8 protons, it will be recognized as oxygen. This atomic number also determines the chemical behavior of an atom, as it dictates the number of electrons that will interact during chemical reactions.

Mass Number

The mass number, different for each isotope, is the sum of an atom's protons and neutrons. It is represented as the upper left superscript in isotope notation. Using oxygen as our reference, which has an atomic number 8, we calculate the mass numbers by adding the neutrons to the protons. For instance, for the three oxygen isotopes with \text{Isotope 1: }${}_8^{16}\text{O}$ having a mass number of 16, \text{Isotope 2: }${}_8^{17}\text{O}$ with a mass number of 17, and \text{Isotope 3: }${}_8^{18}\text{O}$ with a mass number of 18, we see how the differing number of neutrons contributes to the distinct mass numbers. It's critical to note that while the atomic number is consistent within an element, the mass number may vary among different isotopes, influencing both physical and sometimes chemical properties.

Nuclear Composition

Nuclear composition refers to the makeup of an atom's nucleus, including the total count of protons and neutrons. The protons determine the atomic number and, therefore, the element itself, while the neutrons contribute to the isotope's mass and can influence the stability of the atom. For oxygen isotopes, each has the same number of protons (8), but differing numbers of neutrons—8, 9, and 10, respectively. This variation leads to the different isotopes of oxygen, such as \text{Isotope 1: }${}_8^{16}\text{O}$, \text{Isotope 2: }${}_8^{17}\text{O}$, and \text{Isotope 3: }${}_8^{18}\text{O}$. Though chemically similar due to the same number of protons and electrons, these isotopes may have unique physical properties due to the difference in nuclear composition.