An atom that has fewer neutrons than protons and more electrons than protons is a ion

Ok, so a positive ion is called (cation). 
But an atom that has more electrons than protons is a negative ion (anion).

By definition, an atom is electrically neutral (i.e. has the same number of protons as it does electrons, plus some number of neutrons depending on the isotope). If a species were charged, it is referred to as an ion (cation for positively charged and anion for negatively charged species), also by definition.
I believe the answer is anion.

Its trait is different and it the organism survive

Ithink iit might be