Calculating Protons, Neutrons, and Electrons in Atoms and Ions

Introduction

• Understanding how to calculate the number of protons, neutrons, and electrons is essential for studying atomic structure.
• Example used: Sodium (Na).

Key Concepts

Atomic Number and Mass Number

• Atomic Number: The smaller number, indicating the number of protons.
• Mass Number: Larger number, representing a specific isotope of the element.

Calculating Particles

Number of Protons

• Equal to the atomic number.
• Example: Sodium has 11 protons.

Number of Neutrons

• Formula: Mass Number - Atomic Number.
• Example: Sodium-23 has 12 neutrons (23 - 11 = 12).

Number of Electrons in Atoms and Ions

• Neutral Atom: Electrons = Atomic Number.
• Ions: Electrons = Atomic Number - Charge.

Examples

Neutral Atom Example

• Sodium: 11 protons, 12 neutrons, 11 electrons (no charge).

Ion Example 1: Aluminum

• Aluminum-27 with 3+ Charge
  • Atomic Number: 13
  • Protons: 13
  • Neutrons: 14 (27 - 13)
  • Electrons: 10 (13 - 3)

Ion Example 2: Sulfide Ion

• Sulfide Ion
  • Atomic Number: 16
  • Protons: 16
  • Neutrons: 17 (33 - 16)
  • Electrons: 18 (16 - (-2))

Example: Silicon-29

• Silicon-29
  • Atomic Number: 14 (from periodic table)
  • Protons: 14
  • Neutrons: 15 (29 - 14)
  • Electrons: 14 (neutral atom)

Challenge Problem

Identifying Unknown Element

• Given: 4+ cation, 26 neutrons, 18 electrons.
• Process:
  • Use formula: Electrons = Atomic Number - Charge.
  • 18 = Atomic Number - 4 → Atomic Number = 22.
  • Identify element using periodic table: Element 22 is Titanium (Ti).

Additional Calculations

• Mass Number: Neutrons + Atomic Number = 48 (26 + 22).

Conclusion

• Understanding these calculations allows for the identification of elements and their properties based on atomic structure.
• Key to solving problems is the correct use of atomic number, mass number, and charge relationships.