A molecule is the smallest unit of a chemical compound that can exist independently and still retain the chemical properties of that compound.
🔹 It is made up of two or more atoms that are chemically bonded together.
🧬 What is a Molecule Made Of?
A molecule consists of:
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Atoms (of the same or different elements)
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Chemical bonds that hold the atoms together
| Example | Formula | Atoms Involved | Description |
|---|---|---|---|
| Hydrogen gas | H₂ | 2 hydrogen atoms | Simple molecule of one element |
| Oxygen gas | O₂ | 2 oxygen atoms | Needed for breathing |
| Water | H₂O | 2 hydrogen + 1 oxygen | Vital for life |
| Carbon dioxide | CO₂ | 1 carbon + 2 oxygen | Gas we exhale |
| Glucose (sugar) | C₆H₁₂O₆ | Carbon, hydrogen, oxygen | Common energy source in cells |
🔗 How Do Molecules Form?
Atoms join together through chemical bonds. The main types include:
| Bond Type | Description |
|---|---|
| Covalent Bond | Atoms share electrons (e.g. H₂O, CH₄) |
| Ionic Bond | One atom gives and another takes electrons (e.g. NaCl) |
| Metallic Bond | Electrons move freely among metal atoms (common in metals) |
🧪 Types of Molecules
| Type | Definition | Examples |
|---|---|---|
| Simple molecules | Made of the same element | H₂, O₂, N₂ |
| Compound molecules | Made of different elements | H₂O, CO₂ |
| Organic molecules | Contain carbon atoms (often in living things) | Glucose, DNA |
| Inorganic molecules | No carbon or simple carbon compounds | H₂O, NaCl |
🌍 Why Are Molecules Important?
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🧬 They are the building blocks of life (DNA, proteins, water)
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🏭 Used in industry and medicine (drugs, plastics, fuels)
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🍃 Play a role in the environment (oxygen, carbon dioxide, methane)
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⚗️ Make up all matter — solids, liquids, and gases are all made of molecules
📘 Fun Facts About Molecules
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One drop of water contains trillions of H₂O molecules
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Molecules are always in motion (they vibrate, rotate, and move)
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The DNA molecule is the longest and most complex molecule in the human body
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Air is mostly made of nitrogen (N₂) and oxygen (O₂) molecules
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Molecules can be polar (like water) or nonpolar (like oxygen gas)