Extra terrestrial life

Is there life other than on Earth? Nobody directly put me that question till now, but I asked myself and came up with a response. I think there is extra terrestrial life. My reasoning is this, on this planet, life needs oxygen or carbon-di-oxide, water, light. Similarly on another planet or some other satellite life may need nitrogen, hydrogen or a different element altogether. Our scope of knowledge is limited to the elements that we have discovered till now. But there may be many unknown elements in this universe and some of them may support life.