Smd component soldering

Quite possibly, its fairly common to see small smd without marking as there is not much room.

Even ic's can have no markings or have no traceable no's on the net.

If you need transistors they are cheap and not worth salvaging generally.

If you are a beginner though , nothing wrong with trying to identify components.

TL431 seems to be a shunt regulator.

Its a precision voltage reference