Understanding Subatomic Particles and Atomic Structure

Sep 18, 2024

Lecture on Subatomic Particles and Atomic Structure

Introduction

  • Atoms are composed of three main subatomic particles:
    • Protons
    • Neutrons
    • Electrons
  • Each element has atoms with unique numbers and arrangements of these particles.

Characteristics of Subatomic Particles

  • Protons
    • Determine the element's identity.
    • The number of protons is called the atomic number.
  • Neutrons
    • Affect the atom’s mass.
    • The sum of protons and neutrons is called the mass number.
  • Electrons
    • Affect the atom's chemical behavior.
    • Has negligible mass.

Atomic Number

  • Atomic number = number of protons in the nucleus.
  • Example: Carbon (symbol: C) has an atomic number of 6 (6 protons).

Mass Number

  • Mass number = sum of protons and neutrons.
  • Example: Carbon-12 has a mass number of 12 (6 protons + 6 neutrons).

Atomic Mass

  • Total mass of an atom.
  • Measured in Daltons (or atomic mass units).
    • Proton = 1 Dalton
    • Neutron = 1 Dalton
    • Electron ~ 1/2000th of a Dalton (insignificant)

Calculating Atomic Mass

  • Example Carbon-12:
    • 6 protons = 6 Daltons
    • 6 neutrons = 6 Daltons
    • Total = 12 Daltons
  • Atomic mass can be approximated by the mass number (ignoring electrons).

Periodic Table Overview

  • Presented as a series of boxes, each representing an element.
  • Key info in each box:
    • Symbol of the element
    • Atomic number (top left corner)
    • Atomic mass (bottom)
  • Example:
    • Carbon: Atomic mass ≈ 12.011 Daltons

Reading the Periodic Table

  • Read left to right, top to bottom.
  • First element: Hydrogen (Atomic number = 1)
  • Second element: Helium (Atomic number = 2)
  • Continue pattern:
    • Each element has a unique number of protons.
    • No two elements share the same atomic number.

Summary

  • Three kinds of subatomic particles: protons, neutrons, electrons.
  • Atomic number identifies the element.
  • Mass number provides the total number of protons and neutrons.
  • Atomic mass gives the total mass, approximated by the mass number.
  • Understanding atomic structure is key to identifying and distinguishing elements.