Question

Write isotopic notation symbols for each of the following: (a) \(Z=47\), \(A=109\) (b) \(Z=8\), \(A=18\) (c) \(Z=26\), \(A=57\)

Short answer

The isotopic notations are (a) \(^{109}_{47}\text{Ag}\), (b) \(^{18}_{8}\text{O}\), and (c) \(^{57}_{26}\text{Fe}\).

Step-by-step solution

Understanding Isotopic Notation

The isotopic notation for an element is written as \[^A_ZX\]where \(A\) is the mass number (the total number of protons and neutrons), \(Z\) is the atomic number (the number of protons), and \(X\) is the symbol of the element.

Identifying the Element for (a)

Using the periodic table, the element with atomic number \(Z = 47\) is Silver (Ag).

Writing Isotopic Notation for (a)

Using the mass number and the element symbol from Step 2, the isotopic notation for \(Z=47\), \(A=109\) is \[^{109}_{47}\text{Ag}\].

Identifying the Element for (b)

Using the periodic table, the element with atomic number \(Z = 8\) is Oxygen (O).

Writing Isotopic Notation for (b)

Using the mass number and the element symbol from Step 4, the isotopic notation for \(Z=8\), \(A=18\) is \[^{18}_{8}\text{O}\].

Identifying the Element for (c)

Using the periodic table, the element with atomic number \(Z = 26\) is Iron (Fe).

Writing Isotopic Notation for (c)

Using the mass number and the element symbol from Step 6, the isotopic notation for \(Z=26\), \(A=57\) is \[^{57}_{26}\text{Fe}\].

Key concepts

Atomic Number

The atomic number, symbolized as 'Z', is a fundamental concept in chemistry and physics that identifies the number of protons found in the nucleus of an atom. Protons carry a positive charge and are unique to each element. For instance, an atomic number of 8 corresponds to oxygen (O), meaning every atom of oxygen has exactly 8 protons. It's this proton count that determines the element's identity and places it within the periodic table.

The importance of the atomic number becomes evident when we consider isotopes of an element. Isotopes have the same atomic number but differ in the number of neutrons. Thus, while they share chemical properties, their mass can be distinctly different. When students are learning to write isotopic notation, they must accurately identify the atomic number to correctly represent the element in question.

Mass Number

The mass number, denoted as 'A', represents the total number of protons and neutrons in the nucleus of an atom. Unlike the atomic number, the mass number is not a fixed characteristic of an element because each element can have isotopes with different numbers of neutrons. For example, the mass number of an oxygen isotope with 8 protons and 10 neutrons is 18 (mass number = protons + neutrons), which is written as 'O-18' or in isotopic notation as ^{18}_{8}O.

Comprehending the mass number is crucial when distinguishing between isotopes in both natural and synthetic contexts. It aids in calculating the atomic mass of an element, which is an average of the mass numbers of the isotopes weighted by their natural abundance. It's vital to take careful note of the mass number when solving problems in chemistry to ensure accurate representation of isotopes.