Defining a Chemical Substance
📌 A chemical is defined as anything with a defined molecular composition.
🧪 This composition allows one to precisely identify the elements present within the chemical substance.
💧 Examples of defining molecular composition include water (H₂O), which has two hydrogen atoms and one oxygen atom per molecule, and carbon dioxide (CO₂), which has one carbon atom and two oxygen atoms.
⚛️ Substances with a defined molecular composition, like H₂O and CO₂, are considered compounds.

Activity: Developing a Personal Definition
🤔 Students were tasked to individually formulate their own definition for what constitutes a chemical.
🤝 Following individual drafting, students were required to engage in peer review to identify flaws or suggest improvements to their partner's definition.
⏱️ A three-minute time limit was set for the initial drafting phase of the personal definition.

Key Points & Insights
➡️ The core concept defining a chemical is the ability to specify its exact molecular makeup (composition and structure).
➡️ Both water (H₂O) and carbon dioxide (CO₂) serve as clear examples of substances with a defined molecular composition.
➡️ Actionable takeaway: Formulating your own definition and having it critiqued by a peer is an effective method for deepening conceptual understanding.

📸 Video summarized with SummaryTube.com on Nov 17, 2025, 01:49 UTC