Traci... very good....thanks for the replies!
1) I assume that the manufacturer instructions state that a dedicated 120V/20 amp circuit will be required for the new cooktop. Please double check the instructions and/or electrical spec's as most cooktops are 220V circuits and not a 120V circuit.
1A) Will the new cooktop unit be a "plug-in" type to a wall receptacle or will it be "hard-wired"?
2) Your existing 220V receptacle should have a minimum of 3 wires, ie, 2 hots and 1 neutral. The neutral wire may be a white wire or it may be a black wire using a piece of white tape to re-identify it as a neutral wire. If you have Romex cable, take a look at your main electrical panel. If Romex cable, you will most likely have white and yellow cables protruding from the top. If metal conduit, then you will be able to visually determine if it is metal conduit piping. If you have Romex cable, the inside of the existing receptacle box should hopefully have a bare copper ground wire, depending upon the age of the cable and when it was originally installed. You may also have another form of wiring called Flexible Metal Conduit or Armored or BX cable. This type of cable will be metallic and will be spirally wound on the exterior.
3) Depending upon the size of the existing range, your main electrical panel will either have a double pole 30 amp, or 40 amp or 50 amp circuit breaker. Most likely it will either be a 40 or a 50 amp double pole breaker.
4) Let me know what you have and I can walk you thru the process of converting the existing 220V receptacle to a standard 20 amp duplex receptacle. Yes, it is a fairly simple process to convert it back to a standard 120 volt receptacle.
5) If you don't already have one, I would recommend that you borrow one from a friend or a neighbor or purchase a 2-prong AC voltage tester or an AC voltmeter. If purchasing one, these are relatively inexpensive and cost around $25 or less at your local Home Depot or Ace Hardware or Lowe's stores.
6) You will also require a standard 20 amp duplex receptacle, a duplex wall cover plate and some short pieces of jumper wires (12 AWG solid or stranded copper wires, type THHN insulated) in order to transition from the existing large conductors to the smaller 12 AWG conductors to accommodate the new 120V receptacle. You will also require some large plastic wire nuts as the existing wires will need to be spliced with the 12 AWG copper jumper or pigtail wires. You will also require a single pole 20 amp circuit breaker (same brand of breaker) to be installed in the main electrical panel. The new 20 amp will replace your existing double pole 220V breaker.
7) Just reply back to this question and I can walk you thru the process............Thanks........Kevin!