Learning target

By the end of this lesson, I will be able to:

• Describe the difference between elements, molecules, and compounds.

• Identify examples of simple molecules and compounds by reading a chemical formula.

• Explain how atoms come together to make molecules and compounds.

Key Vocabulary

Element
An element is a pure substance made of only one kind of atom. Examples include Oxygen (O) and Hydrogen (H).

Molecule
A molecule forms when 2+ atoms join. They can be the same or different atom types.

Compound
A compound is a molecule with 2+ different elements bonded. Water (H₂O) is an example.

Review

Element

• Substance that cannot be broken down into a simpler form.

• Examples: Hydrogen, Helium, Oxygen, Gold, Magnesium.

• Find them on the Periodic Table of Elements.

​What are Molecules?

A group of two or more atoms held together by chemical bonds.

• Can be the same or different atoms.

• 2 or more different atoms (elements) bonded together.

• Examples: H₂O, CO₂, or C₆H₁₂O₆

Compound

• 2 or more atoms bonded together.

• Can be the same or different atoms (H₂ or H₂O)

Molecule

Molecule vs compound

Compounds

• Compounds are also Molecules.

• Compounds can be separated by chemical means into their components. For example H₂O can be broken into H₂ and O through chemical reactions.

• O

• O₂

• CO₂

• H

• H₂O

• C₆H₁₂O₆

Which of the following are Molecules?
**Think about the definition of a molecule.

Compounds

• H₂O

• C₆H₁₂O₆

• CO₂

Elements

• H

• O

Which of the following are Molecules? (Answers)
**Think about the definition of a molecule.

Molecules

• H₂O

• C₆H₁₂O₆

• O₂

• CO₂

Counting Atoms in chemical Formulas

Chemical formula represents the types (elements) and Number of atoms in a compound/molecule. Example = H₂O or C₆H₁₂O₆

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