Question

Write isotopic symbols in the form \({ }_{Z}^{A} X\) for each isotope. (a) the oxygen isotope with 8 neutrons (b) the fluorine isotope with 10 neutrons (c) the sodium isotope with 12 neutrons (d) the aluminum isotope with 14 neutrons

Short answer

\( { }_{8}^{16} O \), \( { }_{9}^{19} F \), \( { }_{11}^{23} Na \), \( { }_{13}^{27} Al \)

Step-by-step solution

Identifying Oxygen Isotope

Firstly, identify the atomic number (Z) of oxygen from the periodic table, which is 8. Then, calculate the mass number (A) of the isotope by adding the number of protons (equal to atomic number) and the number of neutrons given (8). Therefore, the mass number A is 8 (protons) + 8 (neutrons) = 16.

Writing Oxygen Isotope Symbol

Write the isotopic symbol for oxygen with 8 neutrons using the format \( { }_{Z}^{A} X \), where Z is the atomic number, A is the mass number, and X is the elemental symbol. Thus, the oxygen isotope symbol is \( { }_{8}^{16} O\).

Identifying Fluorine Isotope

Determine the atomic number (Z) of fluorine from the periodic table, which is 9. Calculate the mass number (A) of the isotope by adding the atomic number (9) and the number of neutrons given (10). Therefore, A is 9 (protons) + 10 (neutrons) = 19.

Writing Fluorine Isotope Symbol

Use the isotopic symbol format to write the fluorine isotope with 10 neutrons. The symbol is \( { }_{9}^{19} F\).

Identifying Sodium Isotope

Find the atomic number (Z) of sodium, which is 11. Add this to the given number of neutrons (12) to get the mass number (A): 11 (protons) + 12 (neutrons) = 23.

Writing Sodium Isotope Symbol

The isotopic symbol for the sodium isotope with 12 neutrons is \( { }_{11}^{23} Na\).

Identifying Aluminum Isotope

Locate the atomic number (Z) of aluminum, which is 13. Add this to the number of neutrons given (14) to find the mass number (A): 13 (protons) + 14 (neutrons) = 27.

Writing Aluminum Isotope Symbol

The isotopic symbol for the aluminum isotope with 14 neutrons is \( { }_{13}^{27} Al\).

Key concepts

Atomic Number

In the vast universe of chemistry, the atomic number is a fundamental attribute of a chemical element. This number, often denoted by the symbol 'Z', represents the total count of protons in the nucleus of an atom. It's an unwavering number for each element, and it's what gives an element its unique identity. For instance, all atoms of oxygen have 8 protons, and thus, the atomic number of oxygen is always 8.

The importance of the atomic number comes into play when we look at the periodic table, where elements are arranged by increasing atomic number. It helps us in identifying elements and understanding their properties. When solving problems involving isotopes, like in the given exercise, it's important to remember that while isotopes of the same element have a different number of neutrons, their atomic number remains the same.

Mass Number

Take a step further into the nucleus, and you will encounter the mass number, symbolized as 'A'. It defines the total number of protons and neutrons combined within the core of an atom. Unlike the atomic number, the mass number is not fixed for a given element, as elements usually have different isotopes. Each isotope of an element has the same number of protons but a different number of neutrons, thus leading to a different mass number.

For instance, in the exercise solution for oxygen, by adding the atomic number (8 protons) and the given number of neutrons (8), we get the mass number for a particular oxygen isotope: 16. This mass number is vital for identifying the specific isotope of an element and plays a crucial role in chemical equations and reactions.

Periodic Table

The periodic table is not just a tabular display but a gateway to understanding the universe at an atomic level. This scientific marvel organizes all known chemical elements in an orderly fashion based on their atomic number, electron configurations, and recurring chemical properties. Elements are laid out in rows called periods and columns known as groups.

Within this arrangement, the atomic number increases from left to right and top to bottom. As a powerful tool in chemistry, the periodic table enables students and scientists alike to quickly gather information about elements, including their atomic numbers and relative atomic masses, which are essential when referring to isotopes as shown in the exercise solutions.

Chemical Elements

Chemical elements are the building blocks of all matter. Each element is composed of atoms that have the same atomic number—protons in the nucleus—and is distinguished by its own symbol, like 'O' for oxygen or 'Na' for sodium. At present, there are 118 confirmed elements, a collection of both naturally occurring elements and those synthesized in laboratories.

The diversity among elements stems from variations in the structure of their atoms, especially the number of electrons and neutrons they possess. This variability leads to the vast array of physical and chemical properties characteristic of each element. In our isotopes exercise, by changing the number of neutrons, we investigate different isotopes while staying within the boundaries of the same chemical element.

Neutrons

Neutrons play a silent, yet weighty role in the atom's nucleus. Alongside protons, neutrons contribute to the bulk of an atom's mass, but unlike protons, they don't possess any electric charge. The number of neutrons in an atom can vary even within atoms of the same element, leading to different isotopes. Each isotope of an element, therefore, has its own unique mass number due to the sum of protons (which remains constant) and the number of neutrons (which can differ).

Understanding neutrons is key when analyzing isotopic symbols in the context of our exercise. For example, in fluorine, which always has 9 protons, changing the neutron count from 10 to another number results in different isotopes, like the one represented by the isotopic symbol \( { }_{9}^{19} F\). Neutrons are thus essential for comprehending isotopic differences and the subtleties of atomic structure.