Which diagram represents an element that is likely to form covalent bonds? A purple circle with 2 concentric circles around it. The inner circle has 2 small green spheres. The outer circle has 1 small green sphere. A purple circle with 3 concentric circles around it. The inner circle has 2 small green spheres. The middle circle has 8 small green spheres. The outer circle has 5 small green spheres. A purple circle with 3 concentric circles around it. The inner circle has 2 small green spheres. The middle circle has 8 small green spheres. The outer circle has 8 small green spheres.