What does it mean when components in schematics do not connect?
IC1 has six sections (A-F) although only 4 are used the circuit.

In general it is not allowed to leave inputs of CMOS devices unconnected so the two at the bottom show what to do with the inputs, connect them to ground. Section E also shows how the connections for the power supply pins of the entire device.  The outputs are not used and so are shown as unconnected.

If you did leave the inputs of sections E and F unconnected they could cause incorrect operation of the sections that are used (A-D).

kevin