Molecules: Elements, Compounds & How They Differ - PDF
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Kooringal High School
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This document provides a detailed explanation of molecules, molecules of elements, and molecules of compounds. It discusses their properties, key differences, and examples, including diatomic and polyatomic molecules and ionic compounds. The document covers fundamental concepts in chemistry using illustrations and key takeaways, making it useful for students.
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A Deeper Look at Molecules: Molecules of Compounds vs. Molecules of Elements vs. Compounds The concept of molecules is fundamental in chemistry, but it’s often misunderstood, especially in the distinction between molecules of elements, molecules of compounds, and compounds themselves. Let’s...
A Deeper Look at Molecules: Molecules of Compounds vs. Molecules of Elements vs. Compounds The concept of molecules is fundamental in chemistry, but it’s often misunderstood, especially in the distinction between molecules of elements, molecules of compounds, and compounds themselves. Let’s break them down in depth. 1. What is a Molecule? Key Concept A molecule is a group of two or more atoms chemically bonded together. These atoms can be the same element (e.g., O₂) or different elements (e.g., H₂O). Deeper Explanation: Why and What? Why do molecules form? Atoms combine to achieve a stable electron configuration, typically by sharing electrons (covalent bonding). What makes them unique? Molecules can exist independently as distinct entities, unlike ionic compounds, which form a lattice structure. 2. Molecules of Elements Key Concept A molecule of an element consists of two or more atoms of the same element bonded together. Deeper Explanation: Why and What? Why? Some elements are diatomic or polyatomic, meaning they naturally exist as molecules rather than single atoms because it’s more stable. What makes them unique? They contain only one type of element but still consist of multiple atoms chemically bonded. Examples of Molecules of Elements Diatomic molecules (most common type): ○ Oxygen (O₂) ○ Hydrogen (H₂) ○ Nitrogen (N₂) ○ Chlorine (Cl₂) ○ Fluorine (F₂) ○ Bromine (Br₂) ○ Iodine (I₂) Polyatomic molecules: ○ Ozone (O₃) → Three oxygen atoms bonded together 🔹 Key takeaway: Molecules of elements contain only one type of atom. 3. Molecules of Compounds Key Concept A molecule of a compound consists of two or more different elements chemically bonded together in a fixed ratio. Deeper Explanation: Why and What? Why? When atoms of different elements chemically bond, they form a completely new substance with properties different from the individual elements. What makes them unique? Unlike molecules of elements, molecules of compounds contain multiple types of atoms. Examples of Molecules of Compounds Water (H₂O) → Two hydrogen atoms bonded to one oxygen atom Carbon dioxide (CO₂) → One carbon atom bonded to two oxygen atoms Methane (CH₄) → One carbon atom bonded to four hydrogen atoms 🔹 Key takeaway: Molecules of compounds contain different types of atoms bonded together, creating a new chemical substance. 4. How Are Molecules of Compounds Different from Compounds? Key Concept 🔸 All molecules of compounds are compounds, but not all compounds are molecular. Deeper Explanation: Why and What? Why? A compound is any substance made of two or more different elements chemically bonded, but not all compounds exist as individual molecules. What makes them unique? ○ Molecular Compounds → Exist as distinct molecules (e.g., H₂O, CO₂). ○ Ionic Compounds → Do not form molecules; instead, they form a crystalline lattice (e.g., NaCl, CaCl₂). Examples of Compounds That Are Not Molecular Sodium chloride (NaCl) → Composed of Na⁺ and Cl⁻ ions in a repeating pattern, not individual molecules. Magnesium oxide (MgO) → Forms an ionic lattice rather than discrete molecules. 🔹 Key takeaway: Molecules of compounds refer specifically to covalently bonded substances (like H₂O). Compounds can be either molecular (H₂O) or ionic (NaCl). Final Summary Table: Differences Between These Concepts Concept Definition Key Difference Molecule A group of atoms chemically Can be an element (O₂) or a bonded together. compound (H₂O). Molecules Molecules made of only one Only one type of atom (e.g., of Elements type of element. O₂, N₂, O₃). Molecules Molecules made of different Always contain two or more of elements chemically bonded. types of atoms (e.g., H₂O, Compounds CO₂). Compounds Substances made of two or Can be molecular (H₂O) or more elements chemically ionic (NaCl). bonded.
