Molecular Compounds
A molecular compound is a substance made of molecules formed when atoms bond together by sharing electrons. These bonds are called covalent bonds.
Methane, the gas in a stove’s blue flame, is a molecular compound made of carbon and hydrogen.
Water is another example; it consists of two hydrogen atoms and one oxygen atom.
To name a molecular compound, consider nitrogen oxide; start with the element farthest to the left on the periodic table. Here, it's nitrogen.
Now, add the second element’s name with the suffix “-ide.”, making it oxide. Use prefixes like “di-” when two oxygen atoms are present, such as nitrogen dioxide. Similarly, use “tri-” when three oxygen atoms are present, as in sulfur trioxide.
Scientists often use models to study molecular compounds. Some examples are ball-and-stick models, space-filling models, and Lewis dot structures. These models help visualize how atoms connect and share electrons.
Molecular compounds have unique properties, like low melting points and poor electrical conductivity, which distinguish them from other compounds.
Molecular Compounds
Molecular compounds form when two or more nonmetal atoms share electrons through covalent bonds. Unlike ionic compounds, where electrons are transferred, molecular compounds remain electrically neutral because electrons are shared equally or unequally between atoms.
Common Examples of Molecular Compounds:
- Water (H₂O): Essential for life; it forms hydrogen bonds that give it unique properties.
- Carbon dioxide (CO₂): A gas used by plants in photosynthesis.
- Methane (CH₄): A common fuel source of carbon and hydrogen atoms.
- Ammonia (NH₃): Used in cleaning products and fertilizers.
Science and Engineering Practices (SEP): Developing and Using Models
Scientists create molecular models to visualize how atoms bond and arrange themselves in a compound by studying molecular compounds' physical and chemical properties, such as boiling points, solubility, and reactivity. They also develop new materials, medications, and environmentally friendly products. These discoveries help predict chemical behavior and guide the design of new chemical reactions.
Activity Ideas:
- Molecular Structure Building – Use modeling kits or household objects like beads and sticks to build simple molecular compounds such as HNO3, C6H12O6, or CH₄. Label the atoms and indicate shared electron pairs.
- Physical Properties Investigation – Research and compare various molecular compounds' melting points, boiling points, and physical states. Create a chart showing how molecular size and structure affect these properties.
Crosscutting Concepts (CCC): Patterns
- Pattern: Molecules with similar structures have similar properties.
Example: Methane (CH₄) and ethane (C₂H₆) are hydrocarbons with single covalent bonds, making them good fuel sources. - Pattern: Molecules with polar covalent bonds dissolve well in water, while nonpolar molecules do not.
Example: Sucrose (C₁₂H₂₂O₁₁) dissolves in water due to its polar bonds, while oil (hydrocarbon chains) does not because it is nonpolar. - Pattern: The shape of a molecule affects its function and reactivity.
Example: Ammonia (NH₃) has a bent shape, making it highly soluble in water, while carbon dioxide (CO₂) has a linear shape, allowing it to remain a gas at room temperature.
A molecular compound is a substance made of molecules formed when atoms bond together by sharing electrons. These bonds are called covalent bonds.
Methane, the gas in a stove’s blue flame, is a molecular compound made of carbon and hydrogen.
Water is another example; it consists of two hydrogen atoms and one oxygen atom.
To name a molecular compound, consider nitrogen oxide; start with the element farthest to the left on the periodic table. Here, it's nitrogen.
Now, add the second element’s name with the suffix “-ide.”, making it oxide. Use prefixes like “di-” when two oxygen atoms are present, such as nitrogen dioxide. Similarly, use “tri-” when three oxygen atoms are present, as in sulfur trioxide.
Scientists often use models to study molecular compounds. Some examples are ball-and-stick models, space-filling models, and Lewis dot structures. These models help visualize how atoms connect and share electrons.
Molecular compounds have unique properties, like low melting points and poor electrical conductivity, which distinguish them from other compounds.
A molecular compound is a substance made of molecules formed when atoms bond together by sharing electrons. These bonds are called covalent bonds.
Methane, the gas in a stove’s blue flame, is a molecular compound made of carbon and hydrogen.
Water is another example; it consists of two hydrogen atoms and one oxygen atom.
To name a molecular compound, consider nitrogen oxide; start with the element farthest to the left on the periodic table. Here, it's nitrogen.
Now, add the second element’s name with the suffix “-ide.”, making it oxide. Use prefixes like “di-” when two oxygen atoms are present, such as nitrogen dioxide. Similarly, use “tri-” when three oxygen atoms are present, as in sulfur trioxide.
Scientists often use models to study molecular compounds. Some examples are ball-and-stick models, space-filling models, and Lewis dot structures. These models help visualize how atoms connect and share electrons.
Molecular compounds have unique properties, like low melting points and poor electrical conductivity, which distinguish them from other compounds.
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