Ch.4 Atoms and Elements

Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition

Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook

Timberlake 13th Edition

Ch.4 Atoms and Elements

Problem 84

Chapter 4, Problem 84

Complete the following table for the three naturally occurring isotopes of silicon, the major component in computer chips:

Verified step by step guidance

Step 1: Understand the isotopic symbol format. The isotopic symbol is written as \( ^{A}_{Z}X \), where \( A \) is the mass number (sum of protons and neutrons), \( Z \) is the atomic number (number of protons), and \( X \) is the chemical symbol of the element.

Step 2: Identify the atomic number \( Z \) for silicon. Silicon has an atomic number of 14, meaning it has 14 protons.

Step 3: Determine the mass number \( A \) for each isotope. The three naturally occurring isotopes of silicon are \( ^{28}_{14}Si \), \( ^{29}_{14}Si \), and \( ^{30}_{14}Si \). The mass number is the sum of protons and neutrons.

Step 4: Calculate the number of neutrons for each isotope. Subtract the atomic number \( Z \) from the mass number \( A \): \( \text{Number of neutrons} = A - Z \). For example, \( ^{28}_{14}Si \) has \( 28 - 14 = 14 \) neutrons.

Step 5: Determine the number of electrons. In a neutral atom, the number of electrons equals the number of protons. For silicon isotopes, the number of electrons is 14.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Isotopes

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons. This results in different mass numbers for the isotopes. For example, silicon has three naturally occurring isotopes: Si-28, Si-29, and Si-30, each differing in neutron count while maintaining the same atomic number of 14.

Atomic Number

The atomic number is the number of protons found in the nucleus of an atom and defines the element. For silicon, the atomic number is 14, meaning all silicon isotopes have 14 protons. This number is crucial for determining the element's identity and its position on the periodic table.

Mass Number

The mass number is the total number of protons and neutrons in an atom's nucleus. It is used to distinguish between different isotopes of an element. For instance, the mass numbers of silicon isotopes are 28, 29, and 30, reflecting their varying neutron counts while maintaining the same atomic number.

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Related Practice

Textbook Question

For each representation of a nucleus A through E, write the atomic symbol and identify which are isotopes.

a. <IMAGE>

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Textbook Question

Indicate if the atoms in each pair have the same number of protons, neutrons, or electrons.

c. ⁴⁰₁₈Ar, ³⁹₁₇Cl

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Textbook Question

Consider the following atoms in which X represents the chemical symbol of the element:

¹⁶₈X ¹⁶₉X ¹⁸₁₀X ¹⁷₈X ¹⁸₈X

c. Which atoms have the same mass number?

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Textbook Question

Indicate if each of the following statements is true or false:

c. The atomic mass unit is based on a carbon atom with six protons and six neutrons.

Textbook Question

Consider the following atoms in which X represents the chemical symbol of the element:

¹⁶₈X ¹⁶₉X ¹⁸₁₀X ¹⁷₈X ¹⁸₈X

d. What atoms have the same number of neutrons?

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Textbook Question

Indicate if each of the following statements is true or false:

d. The proton and the electron have about the same mass.