154 Extension Objectives

Proton Number

• Definition: Number of protons in an atom’s nucleus.

• Examples:

  • Hydrogen: 1 proton

  • Oxygen: 8 protons

  • Magnesium: 12 protons

• All atoms of an element have the same proton number, essential for periodic table arrangement.

Nucleon Number

• Definition: Total of protons and neutrons in an atom (mass number).

• Example: Oxygen has 8 protons + 8 neutrons = 16 nucleon number.

  • Provides relative atomic mass.

Periodic Table of Elements

• Lists proton and nucleon numbers.

• Examples:

  • Lithium (Li): Proton 3, Nucleon 7

  • Sodium (Na): Proton 11, Nucleon 23

  • Potassium (K): Proton 19, Nucleon 39

155 Material Properties

Nucleon and Proton Information

• Calculation: Nucleon number = Proton number + Neutron number.

• Examples:

  • Fluorine: 9 protons, 10 neutrons = 19 nucleons

  • Magnesium: 12 protons, 12 neutrons = 24 nucleons

  • Argon: 18 protons, 22 neutrons = 40 nucleons

  • Boron: Proton number = 5, Nucleon number = 11; Neutrons = 6.

Isotopes

• Definition: Atoms of the same element with different neutron counts.

• Examples:

  • Carbon-12: 6 protons, 6 neutrons

  • Carbon-13: 6 protons, 7 neutrons

  • Carbon-14: 6 protons, 8 neutrons

  • Chlorine Isotopes: 75% with 18 neutrons; 25% with 20 neutrons

  • Hydrogen Isotopes: Hydrogen-1 (1 proton), Hydrogen-2 (1 proton + 1 neutron), Hydrogen-3 (1 proton + 2 neutrons).

Summary Definitions

• Proton Number: Count of protons in an atom.

• Nucleon Number: Sum of protons and neutrons.

• Isotopes: Same element with varying neutron counts.

Practice Questions

1. Explain what an isotope is.

2. Determine the proton number and nucleon number for an atom with 15 protons and 16 neutrons.

3. Given a proton number of 19 and a nucleon number of 39, calculate the neutrons.