Lecture Notes: Characteristics of Atoms

Overview

• The lecture discusses how to describe atoms using certain characteristics.
• Key characteristics include: Atomic Number, Mass Number, and Net Charge.

Atomic Number

• Symbol: Z
• Definition: Number of protons in the nucleus of an atom.
• Example: An atom with 3 protons has an atomic number of 3.
• Importance: Determines the type of atom (e.g., carbon, oxygen, sodium).

Mass Number

• Symbol: A
• Definition: Total number of protons and neutrons in the nucleus of an atom.
• Common Misunderstanding: Not just the number of neutrons but protons + neutrons.
• Example: An atom with 3 protons and 4 neutrons has a mass number of 7.

Net Charge

• Definition: Balance of protons' and electrons' charges in an atom.
• Charge Properties:
  • Protons: Positive charge
  • Electrons: Negative charge
• Net charge occurs when the number of protons and electrons differ.
  • Equal protons and electrons = Neutral atom (net charge of 0).
  • More protons than electrons = Positive net charge (ion).
  • More electrons than protons = Negative net charge (ion).
• Examples:
  • 3 protons, 3 electrons = Net charge 0 (neutral)
  • 4 protons, 3 electrons = Net charge +1 (ion)
  • 5 protons, 3 electrons = Net charge +2 (ion)
  • 3 protons, 4 electrons = Net charge -1 (ion)
  • 3 protons, 5 electrons = Net charge -2 (ion)

Summary

• Atoms can be described using atomic number, mass number, and net charge.
• Understanding these characteristics helps in identifying and classifying atoms.

Next Steps

• Practice problems are recommended to reinforce understanding of these concepts.