Question

how many atoms does the phosphorus atom connect to?

Answer 1

Phosphorus has two valencies 3 and 5.

3 - in compounds such as PH3, PCl3, P4O6
5 - PCl5, P4O10

In terms of cordination, the "count" of all the atoms around a P atom it can have 2- 9 atoms around it. Examples are below:-

2 - in OPCH2
3 - in PH3
4 - in PO43-
5 - in PF5
6 - in PF6-
And in some phosphides where there bond is more ionic even higher coordination numbers are known:-

7 - in crystals of Ta2P
8 - in crystals of Hf2P
9 - Ti3P