Can a 17 year old date a child?

Since there is no Rome and Juliet law in California, it is possible for two people, both under the age of 18, to be prosecuted for statutory rape if they engage in sexual intercourse. If a minor is lawfully married to an adult, then they may engage in consensual sex.

Is it okay to talk to a 17 year old?

There is nothing illegal in simply talking to a 17 year old. There can of course be consequences in you engage in any sexual activity with a person under the age of consent. And in California the age of consent is 18 years old.