Query about 4518 Dual 4 bit counter

At the moment I'm a bit of a novice with electronics, but so far, I am doing OK with my first big project. I am running into trouble however, understanding the workings of a chip which I plan to use. There is a good datasheet for it here:

**broken link removed**

The two questions I have are 1) What does the Vdd pin do?
2) Why does this chip have no ground pin?

Any advice/information would be greatly appreciated,

Many thanks, Andy

Vdd is a positive supply pin, Vss the negative pin (normally connect to GND).

Thanks!