Your second question is “if orbitals of 2 atoms overlapp, what kind of bond would be formed?
if the orbitals are overlapping along the same axis such as: two “s” orbitals, or an “s” orbital overlapping with “sp3” hybrid orbital or “Px” overlapping with “Px” then they make sigma bonds. but if the orbitals are overlapping and their axis are parallel to each other such as “Py” overlapping with a “Py” orbital or “Pz” with “Pz” then they form pi bonds. In summary for chem 11 you can say all orbitals overlap to form sigma bonds except “Py” orbital overlap with “Py” or “Pz” with “Pz” which form pi bonds.
