Hydrocarbons are compounds made up of hydrogen and carbon atoms...
Chemistry344 views·Updated 7 Sept 2026·2 pagesUnderstanding Alkanes and Alkenes
paige gibbs@paigegibbs_vuvr
1
of 2
Alkanes - The Saturated Hydrocarbons
Alkanes are like the steady, reliable friends of the hydrocarbon world. Each carbon atom links to four other atoms using single bonds, making them saturated hydrocarbons - they've got the maximum number of hydrogen atoms possible.
These molecules follow the general formula CₙH₂ₙ₊₂. Starting simple: methane (CH₄) has one carbon, ethane (C₂H₆) has two carbons, propane (C₃H₈) has three, and butane (C₄H₁₀) has four. Notice how each carbon is surrounded by hydrogen atoms in a neat, predictable pattern.
Alkanes are fairly unreactive in normal conditions, but they burn brilliantly - that's why we use them as fuels. Shorter chains like methane release energy more quickly when burning, making them perfect for cooking gas.
💡 Remember: The single lines between atoms represent single covalent bonds - one pair of electrons being shared between two atoms.
All alkanes belong to a homologous series, meaning they share the same functional group and follow the same general formula, just with different chain lengths.
2
of 2
Alkenes - The Unsaturated Hydrocarbons
Alkenes are the rebels compared to alkanes - they're unsaturated hydrocarbons with a crucial difference. Instead of all single bonds, they contain at least one C=C double bond, which makes them much more reactive and interesting.
The general formula for alkenes is CₙH₂ₙ - notice there are fewer hydrogen atoms than in alkanes. This happens because the double bond "uses up" some bonding opportunities that hydrogen would normally fill.
Starting with ethene (C₂H₄), then propene (C₃H₆), and butene (C₄H₈), you can see how the pattern develops. The double bond is the star of the show - it's what makes alkenes so useful for making plastics and other materials.
💡 Key insight: The C=C double bond makes alkenes reactive because it can break open to form new bonds with other molecules.
Like alkanes, alkenes form a homologous series with similar chemical properties but gradually changing physical properties like boiling points as the chains get longer.
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Chemistry344 views·Updated 7 Sept 2026·2 pagesUnderstanding Alkanes and Alkenes
paige gibbs@paigegibbs_vuvr
Hydrocarbons are compounds made up of hydrogen and carbon atoms only, and they're everywhere in our daily lives - from the petrol in cars to the gas that heats our homes. Understanding alkanes and alkenes is crucial for your chemistry...
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of 2
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Alkanes - The Saturated Hydrocarbons
Alkanes are like the steady, reliable friends of the hydrocarbon world. Each carbon atom links to four other atoms using single bonds, making them saturated hydrocarbons - they've got the maximum number of hydrogen atoms possible.
These molecules follow the general formula CₙH₂ₙ₊₂. Starting simple: methane (CH₄) has one carbon, ethane (C₂H₆) has two carbons, propane (C₃H₈) has three, and butane (C₄H₁₀) has four. Notice how each carbon is surrounded by hydrogen atoms in a neat, predictable pattern.
Alkanes are fairly unreactive in normal conditions, but they burn brilliantly - that's why we use them as fuels. Shorter chains like methane release energy more quickly when burning, making them perfect for cooking gas.
💡 Remember: The single lines between atoms represent single covalent bonds - one pair of electrons being shared between two atoms.
All alkanes belong to a homologous series, meaning they share the same functional group and follow the same general formula, just with different chain lengths.
2
of 2Sign up to see the content. It's free!
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Alkenes - The Unsaturated Hydrocarbons
Alkenes are the rebels compared to alkanes - they're unsaturated hydrocarbons with a crucial difference. Instead of all single bonds, they contain at least one C=C double bond, which makes them much more reactive and interesting.
The general formula for alkenes is CₙH₂ₙ - notice there are fewer hydrogen atoms than in alkanes. This happens because the double bond "uses up" some bonding opportunities that hydrogen would normally fill.
Starting with ethene (C₂H₄), then propene (C₃H₆), and butene (C₄H₈), you can see how the pattern develops. The double bond is the star of the show - it's what makes alkenes so useful for making plastics and other materials.
💡 Key insight: The C=C double bond makes alkenes reactive because it can break open to form new bonds with other molecules.
Like alkanes, alkenes form a homologous series with similar chemical properties but gradually changing physical properties like boiling points as the chains get longer.
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Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
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