sidechains protruding outwards.
Let's show again the bonds in the backbone, still with hidden sidechains:
between the carbonyl
groups and the nitrogens
in the peptide bonds.
Observe that the helix turns to the right (it is right-handed), as the thread in a screw.
In models for large proteins, the portions with alpha helix conformation are usually rendered in a simplified “cartoon” form as a spiral ribbon