Here's why:

* Electronegativity: Arsenic has an electronegativity of 2.0, which is relatively high. This means it attracts electrons towards itself, but not strongly enough to form ionic bonds.

* Metallic Character: While arsenic exhibits some metallic properties, it's primarily considered a metalloid.

* Bonding Preference: Arsenic readily forms covalent bonds with other nonmetals like oxygen, chlorine, and sulfur. It also forms covalent bonds with metals, forming arsenides.

Examples of arsenic compounds with covalent bonds:

* Arsenic trioxide (As2O3)

* Arsenic sulfide (As2S3)

* Arsine (AsH3)

While arsenic can form ionic bonds in some cases, like in the arsenides (e.g., Na3As), these are less common than covalent bonds.