Smoke alarms go off now that we have a gas stove didn't when we had electric

There are a variety of types of smoke detectors. Those that are most prone to being set off in the way you describe are the ionization type. As you burn gas on your range or in the oven, it produces carbon dioxide and water vapor, both of which can trigger the sensor on an ionization-type smoke detector. These detectors are, however, cheaper to buy and operate as well as more sensitive to fast burning fires that produce little visible smoke.

In areas such as the kitchen or directly outside of a bathroom with a shower it is advisable to use a photoelectric smoke detector in order to avoid false alarms. These detectors are triggered when visible smoke interrupts a light beam, so they are better at detecting smoking, smoldering fires.

Other tips:

Always use the exhaust fan: Cooking is one of the biggest sources of indoor air pollution, so use your vent hood.

Make sure the detector you are tripping isn't a dual smoke/carbon monoxide (CO) detector. Improper combustion from a gas range or oven can create carbon monoxide, an odorless, colorless, poisonous gas. If it is a dual detector and you decide to replace it, make sure to install a dedicated CO detector in the kitchen area. If it goes off you will need to have your range and oven serviced or replaced.

http://depletedcranium.com/the-war-against-ionization-smoke-detectors/

I don't know why gas ranges sometimes cause that problem, but you're not the first I've heard say it. What I can offer is a solution. Buy a shower cap, one of the cheap types that are sometimes offered in hotel rooms.

Slip one of those on the closest smoke detector. Since your detectors are interconnected, removing the battery every time you cook is probably a PIA, if even possible, the shower cap only takes a second. I do that when I sear steaks. I used to remove the batteries, but the shower cap is quicker, easier, and works just as well.

Call the people who installed the range, they might have a more permanent solution. Plus, I'd be concerned that you might have some kind of a small leak, it's worth checking out.

I think you are getting more false alarms is due to the pressure and heat let off by the gas range. The gas is under pressure and the actual flame is combusting causing air currents. One can feel the current even a foot above the flame, which you will not feel on the electric stove. The electric stove only produces dry heat with no use of pressure from the gas. It is this pressure, and of course hot air rises, along with fat/oil vapors. Also if you have a recirculating exhaust, this can also lead to more false alarms, if the filters are not changed/cleaned regularly.

Frying throws droplets of fat into the air. While these droplets are unlikely to set off the smoke alarm themsleves, if they encouter the flame (or even the hot air just above the flame) they will partially burn, leading to smoke. Spitting fat hitting an electric hotplate would have the same effect but is much less likely.

If the flame is well contained under the pan you're much less likely to burn off any fat (also it's more efficient and safer in terms of igniting more fat). A spatter guard might also help (like a lid made of metal mesh).

Depending on the shape of your pan/previous electric hob, there could also be dirt/labels on the bottom of the pan which burn more on the gas. But this is likely to only happen once or twice.