The element that has properties similar to chlorine and fluorine is bromine (Br).

Here's why:

* Halogens: All three elements (chlorine, fluorine, and bromine) belong to Group 17 of the periodic table, known as the halogens.

* Similar Reactivity: Halogens are highly reactive nonmetals. They tend to gain one electron to achieve a stable electron configuration.

* Similar Chemical Properties: All three form diatomic molecules (Cl2, F2, Br2) and share similar reactivity patterns in forming compounds.

Key Differences:

While similar, they do have differences:

* Electronegativity: Fluorine is the most electronegative element, followed by chlorine, then bromine.

* Boiling Points: Bromine is a liquid at room temperature, while chlorine is a gas and fluorine is a gas.

* Reactivity: Fluorine is the most reactive halogen, followed by chlorine, then bromine.

Let me know if you have any other questions!