A certain species X has 17 protons, 18 electrons and 20 neutrons.

(i) What is such a particle called?


(ii) What is the mass number of X?


(iii) What is the atomic number of X?

Number of protons in species X = 17


Electrons = 18


Neutrons = 20


(i) The particle is called an ion because of the more number of the electrons in the atom. There will be a negative charge on the atom due to more electrons, these type of ions are called anions.


(ii) Mass number of X = 17 + 20 = 37


(iii) Atomic number of X = 17


25