[pnicogen1]

We used H2 as represented by 2 s orbitals coming together. The book says that they come together by sigma bonds. A picture of two s orbitals meshing together represents the sigma bond. What I don't understand where the sigma star bonds come from. This is represented by two s orbitals repelling eachother. How can both exist within the same molecule? Am I just misreading the text, because it says that two molecular orbitals for each atomic orbital, but I dont understand how both can exist simultaneously.