An atom of an element is made up of three particles including, proton, electron and neutron. Neutron is a neutral particle so, does not effect the neutrality of an atom. A proton has positive charge and an electron has negative charge. The number of electrons and number of protons in an atom are equal. So, the whole positive charge of protons cancels the while negative charge of electrons in an atom. Therefore, the net charge on an atom is zero and an atom is electrically neutral.
An atom is electronically neutral becuase in an atom protons and electrons are always equal due to which an atom is considered to be neutral.