About isotopes

I'm in year 10 and I have been studying physics and chemistry. When I learned isotopes, I notice that for isotopes, the number of neutron is always higher than that of proton. Is it possible that there are isotopes that the number of neutron is lower than that of proton? If no, is that because repulsion will take place if the number of neutron is lower than that of proton thus making the nucleus easy to spilt up? If I said something wrong or non-sense, please forgive me.