Lecture Notes: Understanding Atoms, Elements, Molecules, and Compounds

Introduction

• Comparison of Lego blocks with atoms:
  • Different colored Lego blocks represent different types of atoms.
  • Just like Lego blocks, atoms are the basic building blocks of matter.

Atoms

• Atoms are the basic building blocks of all matter.
• Everything around us is made up of billions and trillions of atoms.
• Atoms cannot be broken down into smaller particles, similar to Lego blocks.

Elements

• Elements are different types of atoms.
• Examples of elements include:
  • Hydrogen Atom
  • Nitrogen Atom
  • Carbon Atom
• These are referred to as elements on the Periodic Table of Elements.
• An element can contain more than one atom if they are the same type (e.g., two hydrogen atoms together still represent the hydrogen element).

Molecules

• A molecule consists of two or more atoms bonded together.
• Molecules can be formed from:
  • The same type of atoms (e.g., O2)
  • Different types of atoms (e.g., H2O)
• Key point: Molecules must have two or more atoms connected.

Compounds

• Compounds are a type of molecule that contains two or more different elements bonded together.
• Example of compounds:
  • Water (H2O), contains hydrogen and oxygen.
  • Carbon Dioxide (CO2), contains carbon and oxygen.
• Compounds have different elements, whereas molecules can have two or more of the same or different atoms.

Summary Quiz

• Element: Only uses one type of atom from the periodic table.
• Molecule: Has two or more atoms bonded together.
• Compound: Must have two or more different elements bonded together.

Key Understanding

• Atom: Basic building block of matter.
• Element: A pure substance made of only one type of atom.
• Molecule: Two or more atoms bonded together.
• Compound: A molecule that contains at least two different elements.