The addition of bromine (Br₂) to pentene (C₅H₁₀) is a classic example of an electrophilic addition reaction. Here's the breakdown:

1. The Reaction

Pentene, an alkene, has a double bond. Bromine, a diatomic molecule, is an electrophile (electron-seeking). When bromine approaches the double bond, it induces a polarization in the bromine molecule, making one bromine atom slightly positive (δ+) and the other slightly negative (δ-).

2. Mechanism

* Step 1: The slightly positive bromine atom attacks the electron-rich double bond of pentene, breaking the double bond and forming a carbocation intermediate.

* Step 2: The bromide ion (Br⁻) then attacks the carbocation, forming a new carbon-bromine bond.

3. Product

The product of the reaction is 2,3-dibromopentane.

Equation:

```

CH₃CH₂CH=CHCH₃ + Br₂ → CH₃CH₂CHBrCHBrCH₃

```

Important Note: The reaction is stereospecific, meaning the stereochemistry of the product depends on the stereochemistry of the starting alkene. If the pentene is cis, the product will be the cis-dibromopentane. If the pentene is trans, the product will be the trans-dibromopentane.

Let me know if you'd like to see a more detailed mechanism or have any other questions!