Lecture Notes: Characteristics of Atoms

Introduction

• This lesson discusses characteristics used to describe atoms.
• Similar to describing a person's physical traits.

Key Characteristics of Atoms

1. Atomic Number

• Definition: Number of protons in the nucleus of an atom.
• Abbreviation: Often abbreviated as "Z."
• Importance: Defines the type of atom (e.g., carbon, oxygen).
• Example: Atom with 3 protons has an atomic number of 3.

2. Mass Number

• Definition: Total number of protons and neutrons in an atom’s nucleus.
• Abbreviation: Often abbreviated as "A."
• Common Misconception: It's not just the number of neutrons.
• Example: Atom with 3 protons and 4 neutrons has a mass number of 7.

3. Net Charge

• Concept: Balance between protons and electrons.
• Protons: Positive charge.
• Electrons: Negative charge.
• Neutral Atom: Equal number of protons and electrons resulting in a net charge of 0.
• Ion: Atom with a net charge due to imbalance.
  • Positive Ion: More protons than electrons (e.g., +1 charge with 4 protons and 3 electrons).
  • Negative Ion: More electrons than protons (e.g., -1 charge with 3 protons and 4 electrons).

Examples of Net Charge Calculation

• Example 1: 4 electrons and 3 protons = net charge of -1 (more electrons).
• Example 2: 5 electrons and 3 protons = net charge of -2 (more electrons).
• Example 3: 4 protons and 3 electrons = net charge of +1 (more protons).

Conclusion

• Reviewed three key characteristics for describing atoms: atomic number, mass number, and net charge.
• Upcoming video to practice these concepts with examples.