Unused pins - is this a problem? (CMOS quad switch)

[Taylor]

I'm using a 4016be quad bilateral switch, and I only need 2 of the switches in it. Is it a problem to leave the pins to the other 2 unused? Do I need to ground them or anything?

[Mark F]

I was always taught to NOT leave ANY CMOS inputs FLOATING. So, I would suggest you tie the unused inputs to ground.

[Taylor]

Ok, this particular chip's pins are labeled thusly for each switch: in/out 1, out/in 1, cont 1. So should I ground in/out and out/in (I don't really know what the difference is)?

[R.G.]

Mark F is absolutely correct. Never, ever, under any circumstances leave any CMOS input open. The impedance is so high that a few inches of air make a good input resistor. I've seen pros chase phantom intermittent errors for days to weeks because when the local air/humidity/power fields/radio stations changed the thing would work differently, all because of a floating input.

EVERY CMOS INPUT GOES SOMEWHERE EXPLICITLY. NO EXCEPTIONS.

Well, OK, if you like not having projects work...  

The analog ins/outs of the switch should be tied to ground. This doesn't matter so much for CMOS analog switch pins because they're not really inputs, they're current carrying channels. But the control inputs are critical.

[Taylor]

Hmm. Despite that extensive answer, due to my own ignorance with CMOS, I'm actually even more unsure than before.

So the pins labeled "Cont" are the inputs I should ground? And those labeled "in/out" and "out/in" aren't inputs, so they don't matter? Should I just tie all unused pins to ground for simplicity and safety?