📚 Topic Summary
Sigma ($\sigma$) and pi ($\pi$) bonds are types of covalent bonds that differ in their formation and strength. Sigma bonds are formed by the direct, head-on overlap of atomic orbitals, resulting in electron density concentrated along the internuclear axis. They are strong and allow free rotation around the bond. Pi bonds, on the other hand, are formed by the sideways overlap of p-orbitals, resulting in electron density above and below the internuclear axis. They are weaker than sigma bonds and restrict rotation. The presence of pi bonds makes a molecule more reactive, as they are more easily broken than sigma bonds. Think of sigma bonds as the foundation of a stable building, and pi bonds as easily accessible decorations on that building.
🧪 Part A: Vocabulary
Match the following terms with their correct definitions:
| Term |
Definition |
| 1. Sigma Bond |
A. Weaker bond formed by sideways overlap of p-orbitals |
| 2. Pi Bond |
B. The ability of an atom to attract electrons in a chemical bond |
| 3. Reactivity |
C. A molecule containing multiple bonds between atoms |
| 4. Unsaturated Compound |
D. Strong bond formed by head-on overlap of atomic orbitals |
| 5. Electronegativity |
E. The tendency of a substance to undergo chemical reactions |
✍️ Part B: Fill in the Blanks
Complete the following paragraph using the words: sigma, pi, weaker, rotation, stronger.
A ________ bond is formed by the direct overlap of atomic orbitals and is ________ than a ________ bond which is ________ and restricts ________ around the bond axis.
🤔 Part C: Critical Thinking
Explain why molecules with pi bonds are generally more reactive than molecules with only sigma bonds. Provide an example.