Here's why:

* Chlorine's Electronic Configuration: Chlorine has 17 electrons, with the configuration: 1s² 2s² 2p⁶ 3s² 3p⁵

* Valence Electrons: The outermost shell (3s² 3p⁵) has 7 electrons, meaning chlorine needs one more to achieve a stable octet.

* Bonding: Chlorine typically forms one covalent bond, sharing an electron with another atom. This leaves 6 electrons in its outermost shell.

* Lone Pairs: These 6 electrons are arranged in three pairs, which are called lone pairs.

Therefore, Chlorine has three lone pairs of electrons.